test lambdify with mpmath: powm1, log1p, expm1

smichr · Nov 28, 2022 · dc95a77 · dc95a77
1 parent 8ad4f49
commit dc95a77
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Showing 2 changed files with 22 additions and 3 deletions.
diff --git a/sympy/printing/pycode.py b/sympy/printing/pycode.py
@@ -714,8 +714,8 @@ def _print_log2(self, e):
             self._module_format('mpmath.log'), self._print(e.args[0]))
 
     def _print_log1p(self, e):
-        return '{}({}+1)'.format(
-            self._module_format('mpmath.log'), self._print(e.args[0]))
+        return '{}({})'.format(
+            self._module_format('mpmath.log1p'), self._print(e.args[0]))
 
     def _print_Pow(self, expr, rational=False):
         return self._hprint_Pow(expr, rational=rational, sqrt='mpmath.sqrt')

diff --git a/sympy/utilities/tests/test_lambdify.py b/sympy/utilities/tests/test_lambdify.py
@@ -34,7 +34,7 @@
 from sympy.core.expr import UnevaluatedExpr
 from sympy.codegen.cfunctions import expm1, log1p, exp2, log2, log10, hypot
 from sympy.codegen.numpy_nodes import logaddexp, logaddexp2
-from sympy.codegen.scipy_nodes import cosm1
+from sympy.codegen.scipy_nodes import cosm1, powm1
 from sympy.functions.elementary.complexes import re, im, arg
 from sympy.functions.special.polynomials import \
     chebyshevt, chebyshevu, legendre, hermite, laguerre, gegenbauer, \
@@ -190,6 +190,22 @@ def test_mpmath_lambda():
     raises(TypeError, lambda: f(x))
            # if this succeeds, it can't be a mpmath function
 
+    ref2 = (mpmath.mpf("1e-30")
+            - mpmath.mpf("1e-45")/2
+            + 5*mpmath.mpf("1e-60")/6
+            - 3*mpmath.mpf("1e-75")/4
+            + 33*mpmath.mpf("1e-90")/40
+            )
+    f2a = lambdify((x, y), x**y - 1, "mpmath")
+    f2b = lambdify((x, y), powm1(x, y), "mpmath")
+    f2c = lambdify((x,), expm1(x*log1p(x)), "mpmath")
+    ans2a = f2a(mpmath.mpf("1")+mpmath.mpf("1e-15"), mpmath.mpf("1e-15"))
+    ans2b = f2b(mpmath.mpf("1")+mpmath.mpf("1e-15"), mpmath.mpf("1e-15"))
+    ans2c = f2c(mpmath.mpf("1e-15"))
+    assert abs(ans2a - ref2) < 1e-51
+    assert abs(ans2b - ref2) < 1e-67
+    assert abs(ans2c - ref2) < 1e-80
+
 
 @conserve_mpmath_dps
 def test_number_precision():
@@ -1469,6 +1485,9 @@ def test_scipy_special_math():
     cm1 = lambdify((x,), cosm1(x), modules='scipy')
     assert abs(cm1(1e-20) + 5e-41) < 1e-200
 
+    cm2 = lambdify((x, y), powm1(x, y), modules='scipy')
+    assert abs(cm2(1.2, 1e-9) - 1.82321557e-10)  < 1e-17
+
 
 def test_scipy_bernoulli():
     if not scipy: