diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,10 +1,15 @@
-# Changelog for `weierstrass-functions`
-
-## 0.1.1.0 - 2023-03-02
-
-Changes due to the update of 'jacobi-theta'.
-
-
-## 0.1.0.0 - 2023-22-02
-
-First release.
+# Changelog for `weierstrass-functions`
+
+## 0.1.2.0 - 2023-08-24
+
+Simpler and better implementation of `kleinJ`.
+
+
+## 0.1.1.0 - 2023-03-02
+
+Changes due to the update of 'jacobi-theta'.
+
+
+## 0.1.0.0 - 2023-02-22
+
+First release.
diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,30 +1,30 @@
-Copyright Stéphane Laurent (c) 2023
-
-All rights reserved.
-
-Redistribution and use in source and binary forms, with or without
-modification, are permitted provided that the following conditions are met:
-
-    * Redistributions of source code must retain the above copyright
-      notice, this list of conditions and the following disclaimer.
-
-    * Redistributions in binary form must reproduce the above
-      copyright notice, this list of conditions and the following
-      disclaimer in the documentation and/or other materials provided
-      with the distribution.
-
-    * Neither the name of Stéphane Laurent nor the names of other
-      contributors may be used to endorse or promote products derived
-      from this software without specific prior written permission.
-
-THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+Copyright Stéphane Laurent (c) 2023
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Stéphane Laurent nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,8 +1,8 @@
-# weierstrass-functions
-
-<!-- badges: start -->
-[![Stack-lts](https://github.com/stla/weierstrass-functions/actions/workflows/Stack-lts.yml/badge.svg)](https://github.com/stla/weierstrass-functions/actions/workflows/Stack-lts.yml)
-[![Stack-nightly](https://github.com/stla/weierstrass-functions/actions/workflows/Stack-nightly.yml/badge.svg)](https://github.com/stla/weierstrass-functions/actions/workflows/Stack-nightly.yml)
-<!-- badges: end -->
-
+# weierstrass-functions
+
+<!-- badges: start -->
+[![Stack-lts](https://github.com/stla/weierstrass-functions/actions/workflows/Stack-lts.yml/badge.svg)](https://github.com/stla/weierstrass-functions/actions/workflows/Stack-lts.yml)
+[![Stack-nightly](https://github.com/stla/weierstrass-functions/actions/workflows/Stack-nightly.yml/badge.svg)](https://github.com/stla/weierstrass-functions/actions/workflows/Stack-nightly.yml)
+<!-- badges: end -->
+
 Evaluation of the Weierstrass elliptic functions and some related functions.
diff --git a/Setup.hs b/Setup.hs
--- a/Setup.hs
+++ b/Setup.hs
@@ -1,2 +1,2 @@
-import Distribution.Simple
-main = defaultMain
+import Distribution.Simple
+main = defaultMain
diff --git a/src/Internal.hs b/src/Internal.hs
--- a/src/Internal.hs
+++ b/src/Internal.hs
@@ -1,5 +1,5 @@
-module Internal ((%^%)) where
-import Data.Complex ( Complex (..) )
-
-(%^%) :: Complex Double -> Int -> Complex Double
-(%^%) z p = z ^^ p
+module Internal ((%^%)) where
+import Data.Complex ( Complex (..) )
+
+(%^%) :: Complex Double -> Int -> Complex Double
+(%^%) z p = z ^^ p
diff --git a/src/Math/Eisenstein.hs b/src/Math/Eisenstein.hs
--- a/src/Math/Eisenstein.hs
+++ b/src/Math/Eisenstein.hs
@@ -1,122 +1,127 @@
-module Math.Eisenstein
-    ( lambda,
-      eisensteinE2,
-      eisensteinE4,
-      eisensteinE6,
-      kleinJ,
-      kleinJinv,
-      modularDiscriminant,
-      agm,
-      etaDedekind,
-      jtheta1DashDashDash0,
-      jtheta1Dash
-    ) where
-import           Data.Complex           ( Complex(..) )
-import           Internal               ( (%^%) )
-import           Math.EllipticIntegrals ( ellipticF', ellipticE' )
-import           Math.JacobiTheta       ( jtheta2, jtheta3, jtheta4, jtheta1Dash )
-
-
-i_ :: Complex Double
-i_ = 0.0 :+ 1.0
-
--- | Lambda modular function (square of elliptic modulus)
-lambda :: 
-    Complex Double -- ^ tau
- -> Complex Double
-lambda tau = (j2 / j3) %^% 4
-    where
-      q = exp (i_ * pi * tau)
-      j2 = jtheta2 0 q
-      j3 = jtheta3 0 q
-
--- | Eisenstein series of weight 2
-eisensteinE2 :: 
-    Complex Double -- ^ tau
- -> Complex Double
-eisensteinE2 tau = 
-  6 / pi * ellE * j3 - j3 * j3 - j4
-    where
-      q = exp (i_ * pi * tau)
-      j3 = jtheta3 0 q %^% 2
-      j4 = jtheta4 0 q %^% 4
-      ellE = ellipticE' 1e-14 (pi/2) (lambda tau)
-
--- | Eisenstein series of weight 4
-eisensteinE4 :: 
-    Complex Double -- ^ tau
- -> Complex Double
-eisensteinE4 tau = 
-  (jtheta2 0 q %^% 8 + jtheta3 0 q %^% 8 + jtheta4 0 q %^% 8) / 2 
-    where
-      q = exp (i_ * pi * tau)
-
--- | Eisenstein series of weight 6
-eisensteinE6 :: 
-    Complex Double -- ^ tau
- -> Complex Double
-eisensteinE6 tau = 
-  (jtheta3 0 q %^% 12 + jtheta4 0 q %^% 12 - 3 * jtheta2 0 q %^% 8 
-    * (jtheta3 0 q %^% 4 + jtheta4 0 q %^% 4)) / 2
-    where
-      q = exp (i_ * pi * tau)
-
--- | Modular discriminant
-modularDiscriminant ::
-    Complex Double -- ^ tau
- -> Complex Double
-modularDiscriminant tau = 
-  (eisensteinE4 tau %^% 3 - eisensteinE6 tau %^% 2) / 1728
-
--- | Klein J-function
-kleinJ :: 
-    Complex Double -- ^ tau
- -> Complex Double
-kleinJ tau = 
-  eisensteinE4 tau %^% 3 / modularDiscriminant tau
-
--- | Arithmetic-geometric mean
-agm :: 
-    Complex Double -- ^ x 
- -> Complex Double -- ^ y
- -> Complex Double
-agm x y = 
-  if x == 0 || y == 0 || x + y == 0
-    then 0
-    else pi/4 * (x + y) / ellipticF' 1e-15 (pi/2) (((x - y) / (x + y)) %^% 2)
-
--- | Inverse Klein-J function
-kleinJinv :: 
-    Complex Double
- -> Complex Double
-kleinJinv j = 
-  if j == 0
-    then 0.5 :+ (sqrt 3 / 2)
-    else i_ * agm 1 (sqrt(1 - lbd)) / agm 1 (sqrt lbd)
-  where
-    j2 = j * j
-    j3 = j2 * j
-    t = -j3 + 2304 * j2 + 12288 * sqrt(3 * (1728 * j2 - j3)) - 884736 * j
-    u = t ** (1/3)
-    x = 4 + (u - j) / 192 - (1536 * j - j2) / (192 * u)
-    lbd = -(-1 - sqrt(1 - x)) / 2
-
--- | Dedekind eta function
-etaDedekind ::
-    Complex Double -- ^ tau
- -> Complex Double
-etaDedekind tau = exp (ipitau / 12) * j3
-  where
-    ipitau = i_ * pi * tau
-    q = exp (3 * ipitau)
-    j3 = jtheta3 (pi / 2 * (tau + 1)) q
-
--- | Third derivative at 0 of the first Jacobi theta function
-jtheta1DashDashDash0 :: 
-    Complex Double -- ^ tau
- -> Complex Double
-jtheta1DashDashDash0 tau = - jtheta1Dash 0 q * eisensteinE2 tau 
-  where
-    q = exp (i_ * pi * tau)
-
-
+module Math.Eisenstein
+    ( lambda,
+      eisensteinE2,
+      eisensteinE4,
+      eisensteinE6,
+      kleinJ,
+      kleinJinv,
+      modularDiscriminant,
+      agm,
+      etaDedekind,
+      jtheta1DashDashDash0,
+      jtheta1Dash
+    ) where
+import           Data.Complex           ( Complex(..) )
+import           Internal               ( (%^%) )
+import           Math.EllipticIntegrals ( ellipticF', ellipticE' )
+import           Math.JacobiTheta       ( jtheta2, jtheta3, jtheta4, jtheta1Dash )
+
+
+i_ :: Complex Double
+i_ = 0.0 :+ 1.0
+
+-- | Lambda modular function (square of elliptic modulus)
+lambda :: 
+    Complex Double -- ^ tau
+ -> Complex Double
+lambda tau = (j2 / j3) %^% 4
+    where
+      q = exp (i_ * pi * tau)
+      j2 = jtheta2 0 q
+      j3 = jtheta3 0 q
+
+-- | Eisenstein series of weight 2
+eisensteinE2 :: 
+    Complex Double -- ^ tau
+ -> Complex Double
+eisensteinE2 tau = 
+  6 / pi * ellE * j3 - j3 * j3 - j4
+    where
+      q = exp (i_ * pi * tau)
+      j3 = jtheta3 0 q %^% 2
+      j4 = jtheta4 0 q %^% 4
+      ellE = ellipticE' 1e-14 (pi/2) (lambda tau)
+
+-- | Eisenstein series of weight 4
+eisensteinE4 :: 
+    Complex Double -- ^ tau
+ -> Complex Double
+eisensteinE4 tau = 
+  (jtheta2 0 q %^% 8 + jtheta3 0 q %^% 8 + jtheta4 0 q %^% 8) / 2 
+    where
+      q = exp (i_ * pi * tau)
+
+-- | Eisenstein series of weight 6
+eisensteinE6 :: 
+    Complex Double -- ^ tau
+ -> Complex Double
+eisensteinE6 tau = 
+  (jtheta3 0 q %^% 12 + jtheta4 0 q %^% 12 - 3 * jtheta2 0 q %^% 8 
+    * (jtheta3 0 q %^% 4 + jtheta4 0 q %^% 4)) / 2
+    where
+      q = exp (i_ * pi * tau)
+
+-- | Modular discriminant
+modularDiscriminant ::
+    Complex Double -- ^ tau
+ -> Complex Double
+modularDiscriminant tau = 
+  (eisensteinE4 tau %^% 3 - eisensteinE6 tau %^% 2) / 1728
+
+-- | Klein J-function
+kleinJ :: 
+    Complex Double -- ^ tau
+ -> Complex Double
+kleinJ tau = 
+  let 
+  lbd = lambda(tau)
+  x = lbd * (1 - lbd)
+  in
+  256 * (1 - x) %^% 3 / x %^% 2
+  --eisensteinE4 tau %^% 3 / modularDiscriminant tau
+
+-- | Arithmetic-geometric mean
+agm :: 
+    Complex Double -- ^ x 
+ -> Complex Double -- ^ y
+ -> Complex Double
+agm x y = 
+  if x == 0 || y == 0 || x + y == 0
+    then 0
+    else pi/4 * (x + y) / ellipticF' 1e-15 (pi/2) (((x - y) / (x + y)) %^% 2)
+
+-- | Inverse Klein-J function
+kleinJinv :: 
+    Complex Double
+ -> Complex Double
+kleinJinv j = 
+  if j == 0
+    then 0.5 :+ (sqrt 3 / 2)
+    else i_ * agm 1 (sqrt(1 - lbd)) / agm 1 (sqrt lbd)
+  where
+    j2 = j * j
+    j3 = j2 * j
+    t = -j3 + 2304 * j2 + 12288 * sqrt(3 * (1728 * j2 - j3)) - 884736 * j
+    u = t ** (1/3)
+    x = 4 + (u - j) / 192 - (1536 * j - j2) / (192 * u)
+    lbd = -(-1 - sqrt(1 - x)) / 2
+
+-- | Dedekind eta function
+etaDedekind ::
+    Complex Double -- ^ tau
+ -> Complex Double
+etaDedekind tau = exp (ipitau / 12) * j3
+  where
+    ipitau = i_ * pi * tau
+    q = exp (3 * ipitau)
+    j3 = jtheta3 (pi / 2 * (tau + 1)) q
+
+-- | Third derivative at 0 of the first Jacobi theta function
+jtheta1DashDashDash0 :: 
+    Complex Double -- ^ tau
+ -> Complex Double
+jtheta1DashDashDash0 tau = - jtheta1Dash 0 q * eisensteinE2 tau 
+  where
+    q = exp (i_ * pi * tau)
+
+
diff --git a/src/Math/Weierstrass.hs b/src/Math/Weierstrass.hs
--- a/src/Math/Weierstrass.hs
+++ b/src/Math/Weierstrass.hs
@@ -1,191 +1,191 @@
-module Math.Weierstrass
-    ( halfPeriods,
-      ellipticInvariants,
-      weierstrassP,
-      weierstrassPdash,
-      weierstrassPinv,
-      weierstrassSigma,
-      weierstrassZeta
-    ) where
-import           Data.Complex           ( Complex(..) )
-import           Internal               ( (%^%) )
-import           Math.Eisenstein        ( eisensteinE4, 
-                                          eisensteinE6, 
-                                          kleinJinv, 
-                                          jtheta1DashDashDash0 ) 
-import           Math.JacobiTheta       ( jtheta2, 
-                                          jtheta3, 
-                                          jtheta1, 
-                                          jtheta4,
-                                          jtheta1Dash )
-import           Math.Gamma             ( gamma )
-import           Math.EllipticIntegrals ( carlsonRF' )
-
-
-
-i_ :: Complex Double
-i_ = 0.0 :+ 1.0
-
-eisensteinG4 :: Complex Double -> Complex Double
-eisensteinG4 tau = pi %^% 4 / 45 * eisensteinE4 tau
-
-eisensteinG6_over_eisensteinG4 :: Complex Double -> Complex Double
-eisensteinG6_over_eisensteinG4 tau = 
-  2 * pi * pi / 21 * eisensteinE6 tau / eisensteinE4 tau
-
-omega1_and_tau :: 
-  Complex Double -> Complex Double -> (Complex Double, Complex Double)
-omega1_and_tau g2 g3 = (omega1, tau)
-  where
-    (omega1, tau) 
-      | g2 == 0 = 
-        (
-          gamma (1/3) %^% 3 / (4 * pi * g3 ** (1/6)),
-          0.5 :+ (sqrt 3 / 2)
-        )
-      | g3 == 0 = 
-        (
-          i_ * sqrt(sqrt(3.75 * eisensteinG4 tau' / g2)),
-          tau'
-        )
-      | otherwise = 
-        (
-          sqrt(7 * g2 * eisensteinG6_over_eisensteinG4 tau' / (12 * g3)),
-          tau'
-        )
-      where 
-        g2cube = g2 * g2 * g2
-        j = 1728 * g2cube / (g2cube - 27 * g3 * g3)
-        tau' = kleinJinv j
-
--- | Half-periods from elliptic invariants.
-halfPeriods :: 
-    Complex Double -- ^ g2
- -> Complex Double -- ^ g3
- -> (Complex Double, Complex Double) -- ^ omega1, omega2
-halfPeriods g2 g3 = (omega1, tau * omega1)
-  where
-    (omega1, tau) = omega1_and_tau g2 g3
-
-g_from_omega1_and_tau :: 
-  Complex Double -> Complex Double -> (Complex Double, Complex Double)
-g_from_omega1_and_tau omega1 tau = (g2, g3)
-  where
-    q = exp (i_ * pi * tau)
-    j2 = jtheta2 0 q
-    j3 = jtheta3 0 q
-    j2pow4  = j2 %^% 4
-    j2pow8  = j2pow4 * j2pow4
-    j2pow12 = j2pow4 * j2pow8
-    j3pow4  = j3 %^% 4
-    j3pow8  = j3pow4 * j3pow4
-    j3pow12 = j3pow4 * j3pow8
-    g2 = 4/3 * (pi / 2 / omega1) %^% 4 * (j2pow8 - j2pow4 * j3pow4 + j3pow8)
-    g3 = 8/27 * (pi / 2 / omega1) %^% 6 *
-      (j2pow12 - ((1.5 * j2pow8 * j3pow4) + (1.5 * j2pow4 * j3pow8)) + j3pow12)
-
--- | Elliptic invariants from half-periods.
-ellipticInvariants :: 
-    Complex Double -- ^ omega1
- -> Complex Double -- ^ omega2
- -> (Complex Double, Complex Double) -- ^ g2, g3
-ellipticInvariants omega1 omega2 = 
-  g_from_omega1_and_tau omega1 (omega2 / omega1)
-
-weierstrassP_from_tau :: Complex Double -> Complex Double -> Complex Double
-weierstrassP_from_tau z tau = 
-  (pi * j2 * j3 * j4 / j1) %^% 2 - pi * pi * (j2 %^% 4 + j3 %^% 4) / 3
-  where
-    q = exp (i_ * pi * tau)
-    j2 = jtheta2 0 q
-    j3 = jtheta3 0 q
-    z' = pi * z
-    j1 = jtheta1 z' q
-    j4 = jtheta4 z' q
-
-weierstrassP_from_omega :: 
-  Complex Double -> Complex Double -> Complex Double -> Complex Double
-weierstrassP_from_omega z omega1 omega2 = 
-  weierstrassP_from_tau 
-    (z / omega1 / 2) (omega2 / omega1) / (4 * omega1 * omega1)
-
--- | Weierstrass p-function
-weierstrassP ::
-    Complex Double -- ^ z
- -> Complex Double -- ^ elliptic invariant g2
- -> Complex Double -- ^ elliptic invariant g3
- -> Complex Double
-weierstrassP z g2 g3 = weierstrassP_from_omega z omega1 omega2
-  where
-    (omega1, omega2) = halfPeriods g2 g3
-
--- | Derivative of Weierstrass p-function
-weierstrassPdash ::
-    Complex Double -- ^ z
- -> Complex Double -- ^ elliptic invariant g2
- -> Complex Double -- ^ elliptic invariant g3
- -> Complex Double
-weierstrassPdash z g2 g3 = 2 / (w1 %^% 3) * j2 * j3 * j4 * f
-  where
-    (omega1, omega2) = halfPeriods g2 g3
-    w1 = 2 * omega1 / pi
-    tau = omega2 / omega1
-    q = exp (i_ * pi * tau)
-    z' = z / w1 
-    j1 = jtheta1 z' q
-    j2 = jtheta2 z' q
-    j3 = jtheta3 z' q
-    j4 = jtheta4 z' q
-    j1dash = jtheta1Dash 0 q
-    j2zero = jtheta2 0 q
-    j3zero = jtheta3 0 q
-    j4zero = jtheta4 0 q
-    f = j1dash %^% 3 / (j1 %^% 3 * j2zero * j3zero * j4zero)
-
--- | Inverse of Weierstrass p-function
-weierstrassPinv ::
-    Complex Double -- ^ w
- -> Complex Double -- ^ elliptic invariant g2
- -> Complex Double -- ^ elliptic invariant g3
- -> Complex Double
-weierstrassPinv w g2 g3 = carlsonRF' 1e-14 (w - e1) (w - e2) (w - e3)
-  where
-    (omega1, omega2) = halfPeriods g2 g3
-    e1 = weierstrassP omega1 g2 g3
-    e2 = weierstrassP omega2 g2 g3
-    e3 = weierstrassP (-omega1 - omega2) g2 g3
-
--- | Weierstrass sigma function
-weierstrassSigma ::
-    Complex Double -- ^ z
- -> Complex Double -- ^ elliptic invariant g2
- -> Complex Double -- ^ elliptic invariant g3
- -> Complex Double
-weierstrassSigma z g2 g3 = w1 * exp (h * z * z1 / pi) * j1 / j1dash
-  where
-    (omega1, omega2) = halfPeriods g2 g3
-    tau = omega2 / omega1
-    q = exp (i_ * pi * tau)
-    w1 = -2 * omega1 / pi
-    z1 = z / w1
-    j1 = jtheta1 z1 q
-    j1dash = jtheta1Dash 0 q
-    h = - pi / (6 * w1) * jtheta1DashDashDash0 tau / j1dash
-
--- | Weierstrass zeta function
-weierstrassZeta ::
-    Complex Double -- ^ z
- -> Complex Double -- ^ elliptic invariant g2
- -> Complex Double -- ^ elliptic invariant g3
- -> Complex Double
-weierstrassZeta z g2 g3 = - eta1 * z + p * lj1dash
-  where
-    (omega1, omega2) = halfPeriods g2 g3
-    tau = omega2 / omega1
-    q = exp (i_ * pi * tau)
-    w1 = - omega1 / pi
-    p = 0.5 / w1
-    j1dash = jtheta1Dash 0 q
-    eta1 = p * jtheta1DashDashDash0 tau / (6 * w1 * j1dash)
-    pz = p * z
-    lj1dash = jtheta1Dash pz q / jtheta1 pz q
+module Math.Weierstrass
+    ( halfPeriods,
+      ellipticInvariants,
+      weierstrassP,
+      weierstrassPdash,
+      weierstrassPinv,
+      weierstrassSigma,
+      weierstrassZeta
+    ) where
+import           Data.Complex           ( Complex(..) )
+import           Internal               ( (%^%) )
+import           Math.Eisenstein        ( eisensteinE4, 
+                                          eisensteinE6, 
+                                          kleinJinv, 
+                                          jtheta1DashDashDash0 ) 
+import           Math.JacobiTheta       ( jtheta2, 
+                                          jtheta3, 
+                                          jtheta1, 
+                                          jtheta4,
+                                          jtheta1Dash )
+import           Math.Gamma             ( gamma )
+import           Math.EllipticIntegrals ( carlsonRF' )
+
+
+
+i_ :: Complex Double
+i_ = 0.0 :+ 1.0
+
+eisensteinG4 :: Complex Double -> Complex Double
+eisensteinG4 tau = pi %^% 4 / 45 * eisensteinE4 tau
+
+eisensteinG6_over_eisensteinG4 :: Complex Double -> Complex Double
+eisensteinG6_over_eisensteinG4 tau = 
+  2 * pi * pi / 21 * eisensteinE6 tau / eisensteinE4 tau
+
+omega1_and_tau :: 
+  Complex Double -> Complex Double -> (Complex Double, Complex Double)
+omega1_and_tau g2 g3 = (omega1, tau)
+  where
+    (omega1, tau) 
+      | g2 == 0 = 
+        (
+          gamma (1/3) %^% 3 / (4 * pi * g3 ** (1/6)),
+          0.5 :+ (sqrt 3 / 2)
+        )
+      | g3 == 0 = 
+        (
+          i_ * sqrt(sqrt(3.75 * eisensteinG4 tau' / g2)),
+          tau'
+        )
+      | otherwise = 
+        (
+          sqrt(7 * g2 * eisensteinG6_over_eisensteinG4 tau' / (12 * g3)),
+          tau'
+        )
+      where 
+        g2cube = g2 * g2 * g2
+        j = 1728 * g2cube / (g2cube - 27 * g3 * g3)
+        tau' = kleinJinv j
+
+-- | Half-periods from elliptic invariants.
+halfPeriods :: 
+    Complex Double -- ^ g2
+ -> Complex Double -- ^ g3
+ -> (Complex Double, Complex Double) -- ^ omega1, omega2
+halfPeriods g2 g3 = (omega1, tau * omega1)
+  where
+    (omega1, tau) = omega1_and_tau g2 g3
+
+g_from_omega1_and_tau :: 
+  Complex Double -> Complex Double -> (Complex Double, Complex Double)
+g_from_omega1_and_tau omega1 tau = (g2, g3)
+  where
+    q = exp (i_ * pi * tau)
+    j2 = jtheta2 0 q
+    j3 = jtheta3 0 q
+    j2pow4  = j2 %^% 4
+    j2pow8  = j2pow4 * j2pow4
+    j2pow12 = j2pow4 * j2pow8
+    j3pow4  = j3 %^% 4
+    j3pow8  = j3pow4 * j3pow4
+    j3pow12 = j3pow4 * j3pow8
+    g2 = 4/3 * (pi / 2 / omega1) %^% 4 * (j2pow8 - j2pow4 * j3pow4 + j3pow8)
+    g3 = 8/27 * (pi / 2 / omega1) %^% 6 *
+      (j2pow12 - ((1.5 * j2pow8 * j3pow4) + (1.5 * j2pow4 * j3pow8)) + j3pow12)
+
+-- | Elliptic invariants from half-periods.
+ellipticInvariants :: 
+    Complex Double -- ^ omega1
+ -> Complex Double -- ^ omega2
+ -> (Complex Double, Complex Double) -- ^ g2, g3
+ellipticInvariants omega1 omega2 = 
+  g_from_omega1_and_tau omega1 (omega2 / omega1)
+
+weierstrassP_from_tau :: Complex Double -> Complex Double -> Complex Double
+weierstrassP_from_tau z tau = 
+  (pi * j2 * j3 * j4 / j1) %^% 2 - pi * pi * (j2 %^% 4 + j3 %^% 4) / 3
+  where
+    q = exp (i_ * pi * tau)
+    j2 = jtheta2 0 q
+    j3 = jtheta3 0 q
+    z' = pi * z
+    j1 = jtheta1 z' q
+    j4 = jtheta4 z' q
+
+weierstrassP_from_omega :: 
+  Complex Double -> Complex Double -> Complex Double -> Complex Double
+weierstrassP_from_omega z omega1 omega2 = 
+  weierstrassP_from_tau 
+    (z / omega1 / 2) (omega2 / omega1) / (4 * omega1 * omega1)
+
+-- | Weierstrass p-function
+weierstrassP ::
+    Complex Double -- ^ z
+ -> Complex Double -- ^ elliptic invariant g2
+ -> Complex Double -- ^ elliptic invariant g3
+ -> Complex Double
+weierstrassP z g2 g3 = weierstrassP_from_omega z omega1 omega2
+  where
+    (omega1, omega2) = halfPeriods g2 g3
+
+-- | Derivative of Weierstrass p-function
+weierstrassPdash ::
+    Complex Double -- ^ z
+ -> Complex Double -- ^ elliptic invariant g2
+ -> Complex Double -- ^ elliptic invariant g3
+ -> Complex Double
+weierstrassPdash z g2 g3 = 2 / (w1 %^% 3) * j2 * j3 * j4 * f
+  where
+    (omega1, omega2) = halfPeriods g2 g3
+    w1 = 2 * omega1 / pi
+    tau = omega2 / omega1
+    q = exp (i_ * pi * tau)
+    z' = z / w1 
+    j1 = jtheta1 z' q
+    j2 = jtheta2 z' q
+    j3 = jtheta3 z' q
+    j4 = jtheta4 z' q
+    j1dash = jtheta1Dash 0 q
+    j2zero = jtheta2 0 q
+    j3zero = jtheta3 0 q
+    j4zero = jtheta4 0 q
+    f = j1dash %^% 3 / (j1 %^% 3 * j2zero * j3zero * j4zero)
+
+-- | Inverse of Weierstrass p-function
+weierstrassPinv ::
+    Complex Double -- ^ w
+ -> Complex Double -- ^ elliptic invariant g2
+ -> Complex Double -- ^ elliptic invariant g3
+ -> Complex Double
+weierstrassPinv w g2 g3 = carlsonRF' 1e-14 (w - e1) (w - e2) (w - e3)
+  where
+    (omega1, omega2) = halfPeriods g2 g3
+    e1 = weierstrassP omega1 g2 g3
+    e2 = weierstrassP omega2 g2 g3
+    e3 = weierstrassP (-omega1 - omega2) g2 g3
+
+-- | Weierstrass sigma function
+weierstrassSigma ::
+    Complex Double -- ^ z
+ -> Complex Double -- ^ elliptic invariant g2
+ -> Complex Double -- ^ elliptic invariant g3
+ -> Complex Double
+weierstrassSigma z g2 g3 = w1 * exp (h * z * z1 / pi) * j1 / j1dash
+  where
+    (omega1, omega2) = halfPeriods g2 g3
+    tau = omega2 / omega1
+    q = exp (i_ * pi * tau)
+    w1 = -2 * omega1 / pi
+    z1 = z / w1
+    j1 = jtheta1 z1 q
+    j1dash = jtheta1Dash 0 q
+    h = - pi / (6 * w1) * jtheta1DashDashDash0 tau / j1dash
+
+-- | Weierstrass zeta function
+weierstrassZeta ::
+    Complex Double -- ^ z
+ -> Complex Double -- ^ elliptic invariant g2
+ -> Complex Double -- ^ elliptic invariant g3
+ -> Complex Double
+weierstrassZeta z g2 g3 = - eta1 * z + p * lj1dash
+  where
+    (omega1, omega2) = halfPeriods g2 g3
+    tau = omega2 / omega1
+    q = exp (i_ * pi * tau)
+    w1 = - omega1 / pi
+    p = 0.5 / w1
+    j1dash = jtheta1Dash 0 q
+    eta1 = p * jtheta1DashDashDash0 tau / (6 * w1 * j1dash)
+    pz = p * z
+    lj1dash = jtheta1Dash pz q / jtheta1 pz q
diff --git a/tests/Approx.hs b/tests/Approx.hs
--- a/tests/Approx.hs
+++ b/tests/Approx.hs
@@ -1,15 +1,15 @@
-module Approx (assertApproxEqual) where
-import           Data.Complex     ( imagPart, realPart, Complex(..) )
-import           Test.Tasty.HUnit ( Assertion, assertEqual )
-
--- round x to n digits
-approx0 :: Int -> Double -> Double
-approx0 n x = fromInteger (round $ x * (10^n)) / (10.0^^n)
-
--- round z to n digits
-approx :: Int -> Complex Double -> Complex Double
-approx n z = approx0 n (realPart z) :+ approx0 n (imagPart z)
-
-assertApproxEqual :: String -> Int -> Complex Double -> Complex Double -> Assertion
-assertApproxEqual prefix n z1 z2 = 
-  assertEqual prefix (approx n z1) (approx n z2)
+module Approx (assertApproxEqual) where
+import           Data.Complex     ( imagPart, realPart, Complex(..) )
+import           Test.Tasty.HUnit ( Assertion, assertEqual )
+
+-- round x to n digits
+approx0 :: Int -> Double -> Double
+approx0 n x = fromInteger (round $ x * (10^n)) / (10.0^^n)
+
+-- round z to n digits
+approx :: Int -> Complex Double -> Complex Double
+approx n z = approx0 n (realPart z) :+ approx0 n (imagPart z)
+
+assertApproxEqual :: String -> Int -> Complex Double -> Complex Double -> Assertion
+assertApproxEqual prefix n z1 z2 = 
+  assertEqual prefix (approx n z1) (approx n z2)
diff --git a/tests/Main.hs b/tests/Main.hs
--- a/tests/Main.hs
+++ b/tests/Main.hs
@@ -1,144 +1,153 @@
-module Main where
-import           Approx               ( assertApproxEqual )
-import           Data.Complex         ( Complex(..) )
-import           Math.Eisenstein      ( eisensteinE4,
-                                        eisensteinE6,
-                                        kleinJ,
-                                        agm,
-                                        kleinJinv, 
-                                        etaDedekind,
-                                        lambda )
-import           Math.Gamma           ( gamma )
-import           Test.Tasty           ( defaultMain, testGroup )
-import           Test.Tasty.HUnit     ( testCase )
-import           Math.Weierstrass     ( halfPeriods, 
-                                        ellipticInvariants,
-                                        weierstrassP,
-                                        weierstrassPdash,
-                                        weierstrassPinv,
-                                        weierstrassSigma,
-                                        weierstrassZeta )
-
-i_ :: Complex Double
-i_ = 0.0 :+ 1.0
-
-tau1 :: Complex Double 
-tau1 = i_
-
-tau2 :: Complex Double 
-tau2 = i_ / 10.0
-
-tau3 :: Complex Double 
-tau3 = 2.0 :+ 2.0
-
-main :: IO ()
-main = defaultMain $
-  testGroup "Tests"
-  [ 
-    testCase "E4 is modular - condition 1" $ do
-      let e4_tau   = eisensteinE4 tau1 
-          e4_taup1 = eisensteinE4 (tau1 + 1)
-      assertApproxEqual "" 12 e4_tau e4_taup1,
-
-    testCase "E4 is modular - condition 2" $ do
-      let e4  = eisensteinE4 (-1 / tau2) 
-          e4' = tau2**4 * eisensteinE4 tau2
-      assertApproxEqual "" 12 e4 e4',
-
-    testCase "E6 is modular - condition 1" $ do
-      let e6_tau   = eisensteinE6 tau2 
-          e6_taup1 = eisensteinE6 (tau2 + 1)
-      assertApproxEqual "" 7 e6_tau e6_taup1,
-
-    testCase "E6 is modular - condition 2" $ do
-      let e6  = eisensteinE6 (-1 / tau3) 
-          e6' = tau3**6 * eisensteinE6 tau3
-      assertApproxEqual "" 10 e6 e6',
-
-    testCase "a value of Klein J-function" $ do
-      let expected = 66**3
-          obtained = kleinJ (2 * i_)
-      assertApproxEqual "" 7 expected obtained,
-
-    testCase "a value of agm" $ do
-      let expected = 2 * pi ** 1.5 * sqrt 2 / gamma 0.25 ** 2
-          obtained = agm 1 (sqrt 2)
-      assertApproxEqual "" 14 expected obtained,
-
-    testCase "kleinJ o kleinJinv = id" $ do
-      let expected =  0.2 :+ 0.2
-          obtained = kleinJ (kleinJinv (0.2 :+ 0.2))
-      assertApproxEqual "" 12 expected obtained,
-
-    testCase "Elliptic invariants - 1/2" $ do
-      let g2 = (-7) :+ 9
-          g3 = 5 :+ 3
-          (omega1, omega2) = halfPeriods g2 g3
-          (g2', _) = ellipticInvariants omega1 omega2
-      assertApproxEqual "" 12 g2 g2',
-
-    testCase "Elliptic invariants - 2/2" $ do
-      let g2 = (-7) :+ 9
-          g3 = 5 :+ 3
-          (omega1, omega2) = halfPeriods g2 g3
-          (_, g3') = ellipticInvariants omega1 omega2
-      assertApproxEqual "" 12 g3 g3',
-
-    testCase "a value of weierstrassP" $ do
-      let z = 0.1 :+ 0.1
-          g2 = 2 :+ 1
-          g3 = 2 :+ (-1)
-          obtained = weierstrassP z g2 g3
-          expected = (-0.0010285443715) :+ (-49.9979857342848)
-      assertApproxEqual "" 11 expected obtained,
-
-    testCase "Equianharmonic case" $ do
-      let omega2 = gamma (1/3) ** 3 / 4 / pi
-          z0 = omega2 * (1 :+ (1 / sqrt 3))
-          obtained = weierstrassP z0 0 1
-          expected = 0
-      assertApproxEqual "" 13 obtained expected,
-
-    testCase "Differential equation" $ do
-      let z = 1 :+ 1
-          g2 = 2 :+ 1
-          g3 = 2 :+ (-1)
-          w = weierstrassP z g2 g3
-          wdash = weierstrassPdash z g2 g3
-          left = wdash ** 2
-          right = 4 * w ** 3 - g2 * w - g3
-      assertApproxEqual "" 11 left right,
-
-    testCase "weierstrassPinv works" $ do
-      let w = 0.1 :+ 1
-          g2 = 2 :+ 2
-          g3 = 0 :+ 3
-          z = weierstrassPinv w g2 g3
-          obtained = weierstrassP z g2 g3
-          expected = w
-      assertApproxEqual "" 13 expected obtained,
-
-    testCase "a value of Dedekind eta" $ do
-      let expected = gamma 0.25 / 2 ** (11/8) / pi ** 0.75
-          obtained = etaDedekind (2 * i_)
-      assertApproxEqual "" 14 expected obtained,
-
-    testCase "lambda modular identity" $ do
-      let x = sqrt 2
-          expected = 1
-          obtained = lambda (i_ * x) + lambda (i_ / x)
-      assertApproxEqual "" 14 expected obtained,
-
-    testCase "a value of weierstrassSigma" $ do
-      let expected = 1.8646253716 :+ (-0.3066001355)
-          obtained = weierstrassSigma 2 1 (2 * i_)
-      assertApproxEqual "" 10 expected obtained,
-
-    testCase "a value of weierstrassZeta" $ do
-      let g2 = 5 :+ 3
-          g3 = 5 :+ 3
-          expected = 0.802084165492408 :+ (-0.381791358666872)
-          obtained = weierstrassZeta (1 :+ 1) g2 g3
-      assertApproxEqual "" 13 expected obtained
-
-  ]
+module Main where
+import           Approx               ( assertApproxEqual )
+import           Data.Complex         ( Complex(..) )
+import           Math.Eisenstein      ( eisensteinE4,
+                                        eisensteinE6,
+                                        modularDiscriminant,
+                                        kleinJ,
+                                        agm,
+                                        kleinJinv, 
+                                        etaDedekind,
+                                        lambda )
+import           Math.Gamma           ( gamma )
+import           Test.Tasty           ( defaultMain, testGroup )
+import           Test.Tasty.HUnit     ( testCase )
+import           Math.Weierstrass     ( halfPeriods, 
+                                        ellipticInvariants,
+                                        weierstrassP,
+                                        weierstrassPdash,
+                                        weierstrassPinv,
+                                        weierstrassSigma,
+                                        weierstrassZeta )
+
+i_ :: Complex Double
+i_ = 0.0 :+ 1.0
+
+tau1 :: Complex Double 
+tau1 = i_
+
+tau2 :: Complex Double 
+tau2 = i_ / 10.0
+
+tau3 :: Complex Double 
+tau3 = 2.0 :+ 2.0
+
+tau4 :: Complex Double 
+tau4 = 0.2 :+ 0.2
+
+main :: IO ()
+main = defaultMain $
+  testGroup "Tests"
+  [ 
+    testCase "E4 is modular - condition 1" $ do
+      let e4_tau   = eisensteinE4 tau1 
+          e4_taup1 = eisensteinE4 (tau1 + 1)
+      assertApproxEqual "" 12 e4_tau e4_taup1,
+
+    testCase "E4 is modular - condition 2" $ do
+      let e4  = eisensteinE4 (-1 / tau2) 
+          e4' = tau2**4 * eisensteinE4 tau2
+      assertApproxEqual "" 12 e4 e4',
+
+    testCase "E6 is modular - condition 1" $ do
+      let e6_tau   = eisensteinE6 tau2 
+          e6_taup1 = eisensteinE6 (tau2 + 1)
+      assertApproxEqual "" 7 e6_tau e6_taup1,
+
+    testCase "E6 is modular - condition 2" $ do
+      let e6  = eisensteinE6 (-1 / tau3) 
+          e6' = tau3**6 * eisensteinE6 tau3
+      assertApproxEqual "" 10 e6 e6',
+
+    testCase "a value of Klein J-function" $ do
+      let expected = 66**3
+          obtained = kleinJ (2 * i_)
+      assertApproxEqual "" 7 expected obtained,
+
+    testCase "a value of agm" $ do
+      let expected = 2 * pi ** 1.5 * sqrt 2 / gamma 0.25 ** 2
+          obtained = agm 1 (sqrt 2)
+      assertApproxEqual "" 14 expected obtained,
+
+    testCase "kleinJ o kleinJinv = id" $ do
+      let expected =  0.2 :+ 0.2
+          obtained = kleinJ (kleinJinv (0.2 :+ 0.2))
+      assertApproxEqual "" 12 expected obtained,
+
+    testCase "kleinJ - alternative expression" $ do
+      let k = kleinJ tau3
+          k' = (eisensteinE4 tau3)**3 / modularDiscriminant tau3
+      assertApproxEqual "" 4 k k',
+
+    testCase "Elliptic invariants - 1/2" $ do
+      let g2 = (-7) :+ 9
+          g3 = 5 :+ 3
+          (omega1, omega2) = halfPeriods g2 g3
+          (g2', _) = ellipticInvariants omega1 omega2
+      assertApproxEqual "" 12 g2 g2',
+
+    testCase "Elliptic invariants - 2/2" $ do
+      let g2 = (-7) :+ 9
+          g3 = 5 :+ 3
+          (omega1, omega2) = halfPeriods g2 g3
+          (_, g3') = ellipticInvariants omega1 omega2
+      assertApproxEqual "" 12 g3 g3',
+
+    testCase "a value of weierstrassP" $ do
+      let z = 0.1 :+ 0.1
+          g2 = 2 :+ 1
+          g3 = 2 :+ (-1)
+          obtained = weierstrassP z g2 g3
+          expected = (-0.0010285443715) :+ (-49.9979857342848)
+      assertApproxEqual "" 11 expected obtained,
+
+    testCase "Equianharmonic case" $ do
+      let omega2 = gamma (1/3) ** 3 / 4 / pi
+          z0 = omega2 * (1 :+ (1 / sqrt 3))
+          obtained = weierstrassP z0 0 1
+          expected = 0
+      assertApproxEqual "" 13 obtained expected,
+
+    testCase "Differential equation" $ do
+      let z = 1 :+ 1
+          g2 = 2 :+ 1
+          g3 = 2 :+ (-1)
+          w = weierstrassP z g2 g3
+          wdash = weierstrassPdash z g2 g3
+          left = wdash ** 2
+          right = 4 * w ** 3 - g2 * w - g3
+      assertApproxEqual "" 11 left right,
+
+    testCase "weierstrassPinv works" $ do
+      let w = 0.1 :+ 1
+          g2 = 2 :+ 2
+          g3 = 0 :+ 3
+          z = weierstrassPinv w g2 g3
+          obtained = weierstrassP z g2 g3
+          expected = w
+      assertApproxEqual "" 13 expected obtained,
+
+    testCase "a value of Dedekind eta" $ do
+      let expected = gamma 0.25 / 2 ** (11/8) / pi ** 0.75
+          obtained = etaDedekind (2 * i_)
+      assertApproxEqual "" 14 expected obtained,
+
+    testCase "lambda modular identity" $ do
+      let x = sqrt 2
+          expected = 1
+          obtained = lambda (i_ * x) + lambda (i_ / x)
+      assertApproxEqual "" 14 expected obtained,
+
+    testCase "a value of weierstrassSigma" $ do
+      let expected = 1.8646253716 :+ (-0.3066001355)
+          obtained = weierstrassSigma 2 1 (2 * i_)
+      assertApproxEqual "" 10 expected obtained,
+
+    testCase "a value of weierstrassZeta" $ do
+      let g2 = 5 :+ 3
+          g3 = 5 :+ 3
+          expected = 0.802084165492408 :+ (-0.381791358666872)
+          obtained = weierstrassZeta (1 :+ 1) g2 g3
+      assertApproxEqual "" 13 expected obtained
+
+  ]
diff --git a/weierstrass-functions.cabal b/weierstrass-functions.cabal
--- a/weierstrass-functions.cabal
+++ b/weierstrass-functions.cabal
@@ -1,51 +1,51 @@
-name:                weierstrass-functions
-version:             0.1.1.0
-synopsis:            Weierstrass Elliptic Functions
-description:         Evaluation of Weierstrass elliptic functions and some related functions.
-homepage:            https://github.com/stla/weierstrass-functions#readme
-license:             BSD3
-license-file:        LICENSE
-author:              Stéphane Laurent
-maintainer:          laurent_step@outlook.fr
-copyright:           2023 Stéphane Laurent
-category:            Math, Numeric
-build-type:          Simple
-extra-source-files:  README.md
-                     CHANGELOG.md
-cabal-version:       >=1.10
-
-library
-  hs-source-dirs:      src
-  exposed-modules:     Math.Eisenstein
-                     , Math.Weierstrass
-  other-modules:       Internal
-  build-depends:       base >= 4.7 && < 5
-                     , jacobi-theta >= 0.1.2.0
-                     , elliptic-integrals >= 0.1.0.0
-                     , gamma >= 0.10.0.0
-  default-language:    Haskell2010
-  ghc-options:         -Wall
-                       -Wcompat
-                       -Widentities
-                       -Wincomplete-record-updates
-                       -Wincomplete-uni-patterns
-                       -Wmissing-export-lists
-                       -Wmissing-home-modules
-                       -Wpartial-fields
-                       -Wredundant-constraints
-
-test-suite unit-tests
-  type:                 exitcode-stdio-1.0
-  main-is:              Main.hs
-  hs-source-dirs:       tests/
-  other-modules:        Approx
-  Build-Depends:        base >= 4.7 && < 5
-                      , tasty
-                      , tasty-hunit
-                      , weierstrass-functions
-                      , gamma >= 0.10.0.0
-  Default-Language:     Haskell2010
-
-source-repository head
-  type:     git
-  location: https://github.com/stla/weierstrass-functions
+name:                weierstrass-functions
+version:             0.1.2.0
+synopsis:            Weierstrass Elliptic Functions
+description:         Evaluation of Weierstrass elliptic functions and some related functions.
+homepage:            https://github.com/stla/weierstrass-functions#readme
+license:             BSD3
+license-file:        LICENSE
+author:              Stéphane Laurent
+maintainer:          laurent_step@outlook.fr
+copyright:           2023 Stéphane Laurent
+category:            Math, Numeric
+build-type:          Simple
+extra-source-files:  README.md
+                     CHANGELOG.md
+cabal-version:       >=1.10
+
+library
+  hs-source-dirs:      src
+  exposed-modules:     Math.Eisenstein
+                     , Math.Weierstrass
+  other-modules:       Internal
+  build-depends:       base >= 4.7 && < 5
+                     , jacobi-theta >= 0.1.2.0
+                     , elliptic-integrals >= 0.1.0.0
+                     , gamma >= 0.10.0.0
+  default-language:    Haskell2010
+  ghc-options:         -Wall
+                       -Wcompat
+                       -Widentities
+                       -Wincomplete-record-updates
+                       -Wincomplete-uni-patterns
+                       -Wmissing-export-lists
+                       -Wmissing-home-modules
+                       -Wpartial-fields
+                       -Wredundant-constraints
+
+test-suite unit-tests
+  type:                 exitcode-stdio-1.0
+  main-is:              Main.hs
+  hs-source-dirs:       tests/
+  other-modules:        Approx
+  Build-Depends:        base >= 4.7 && < 5
+                      , tasty
+                      , tasty-hunit
+                      , weierstrass-functions
+                      , gamma >= 0.10.0.0
+  Default-Language:     Haskell2010
+
+source-repository head
+  type:     git
+  location: https://github.com/stla/weierstrass-functions