Merge pull request sympy#16534 from cbm755/octave_gammainc

asmeurer · web-flow · commit ce6176fa3918 · 2019-04-03T12:48:00.000-05:00
octave codegen: they have regularized incomplete gamma fcn
diff --git a/sympy/printing/octave.py b/sympy/printing/octave.py
@@ -401,14 +401,15 @@ def _print_Identity(self, expr):
         return "eye(" + s + ")"
 
 
-    def _print_uppergamma(self, expr):
-        return "gammainc(%s, %s, 'upper')" % (self._print(expr.args[1]),
-                                              self._print(expr.args[0]))
+    def _print_lowergamma(self, expr):
+        # Octave implements regularized incomplete gamma function
+        return "(gammainc({1}, {0}).*gamma({0}))".format(
+            self._print(expr.args[0]), self._print(expr.args[1]))
 
 
-    def _print_lowergamma(self, expr):
-        return "gammainc(%s, %s, 'lower')" % (self._print(expr.args[1]),
-                                              self._print(expr.args[0]))
+    def _print_uppergamma(self, expr):
+        return "(gammainc({1}, {0}, 'upper').*gamma({0}))".format(
+            self._print(expr.args[0]), self._print(expr.args[1]))
 
 
     def _print_sinc(self, expr):
diff --git a/sympy/printing/tests/test_octave.py b/sympy/printing/tests/test_octave.py
@@ -463,8 +463,9 @@ def test_specfun():
     assert octave_code(airyaiprime(x)) == 'airy(1, x)'
     assert octave_code(airybi(x)) == 'airy(2, x)'
     assert octave_code(airybiprime(x)) == 'airy(3, x)'
-    assert octave_code(uppergamma(n, x)) == 'gammainc(x, n, \'upper\')'
-    assert octave_code(lowergamma(n, x)) == 'gammainc(x, n, \'lower\')'
+    assert octave_code(uppergamma(n, x)) == '(gammainc(x, n, \'upper\').*gamma(n))'
+    assert octave_code(lowergamma(n, x)) == '(gammainc(x, n).*gamma(n))'
+    assert octave_code(z**lowergamma(n, x)) == 'z.^(gammainc(x, n).*gamma(n))'
     assert octave_code(jn(n, x)) == 'sqrt(2)*sqrt(pi)*sqrt(1./x).*besselj(n + 1/2, x)/2'
     assert octave_code(yn(n, x)) == 'sqrt(2)*sqrt(pi)*sqrt(1./x).*bessely(n + 1/2, x)/2'
     assert octave_code(LambertW(x)) == 'lambertw(x)'
