This fixes traceback for calculating integrals like a**x + b*x and also
ratint(x, x).
Although I'm not really sure if it is a proper fix (for me it looks more
like a workaround), but you guys know better ;)
You can either check from here:
https://code.plaes.org/git/sympy.git/commit/?h=issue-1417
or the attachment..
Cheers,
Priit :)
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>From 8bd1d50ab2092f464edfc9e5ee04fcee3623e21e Mon Sep 17 00:00:00 2001
From: Priit Laes <pl...@plaes.org>
Date: Tue, 12 May 2009 22:23:35 +0300
Subject: [PATCH] Fix integrals containing sums with simple coeff*x term. Fixes bug #1417.
---
sympy/integrals/rationaltools.py | 6 +++++-
sympy/integrals/tests/test_integrals.py | 3 +++
sympy/integrals/tests/test_rationaltools.py | 2 ++
3 files changed, 10 insertions(+), 1 deletions(-)
diff --git a/sympy/integrals/rationaltools.py b/sympy/integrals/rationaltools.py
index 97657e0..38d3965 100644
--- a/sympy/integrals/rationaltools.py
+++ b/sympy/integrals/rationaltools.py
@@ -1,7 +1,7 @@
"""This module implements tools for integrating rational functions. """
from sympy import S, Symbol, symbols, I, log, atan, Poly, \
- div, quo, resultant, roots, collect, solve, RootSum, Lambda
+ div, quo, resultant, roots, collect, solve, RootSum, Lambda, Rational
from sympy.polys.algorithms import poly_div, poly_gcd, \
poly_gcdex, poly_sqf, poly_subresultants
@@ -26,6 +26,10 @@ def ratint(f, x, **flags):
Functions, Second Edition, Springer-Verlang, 2005, pp. 35-70
"""
+ # Return early when f(x) = x
+ if f is x:
+ return x*x/Rational(2)
+
if type(f) is not tuple:
p, q = f.as_numer_denom()
else:
diff --git a/sympy/integrals/tests/test_integrals.py b/sympy/integrals/tests/test_integrals.py
index 301090c..0483f4b 100644
--- a/sympy/integrals/tests/test_integrals.py
+++ b/sympy/integrals/tests/test_integrals.py
@@ -339,3 +339,6 @@ def test_subs5():
def test_integration_variable():
raises(ValueError, "Integral(exp(-x**2), 3)")
raises(ValueError, "Integral(exp(-x**2), (3, -oo, oo))")
+
+def test_issue_1417():
+ assert integrate(2**x - 5*x**2, x) == 2**x/log(2) - 5*x**3/3
diff --git a/sympy/integrals/tests/test_rationaltools.py b/sympy/integrals/tests/test_rationaltools.py
index e212b60..4cd53dd 100644
--- a/sympy/integrals/tests/test_rationaltools.py
+++ b/sympy/integrals/tests/test_rationaltools.py
@@ -50,3 +50,5 @@ def test_ratint():
x + S(1)/2*x**2 + S(1)/2*log(2-x+x**2) + (S(9)/7-4*x/7)/(2-x+x**2) + \
13*7**(S(1)/2)*atan(-S(1)/7*7**(S(1)/2) + 2*x*7**(S(1)/2)/7)/49
+ # issue #1417
+ assert ratint(x, x) == x**2/2
--
1.6.3
