[Boost-commit] svn:boost r51059 - in trunk: boost/math/special_functions/detail libs/math/test

Subject: [Boost-commit] svn:boost r51059 - in trunk: boost/math/special_functions/detail libs/math/test
From: john_at_[hidden]
Date: 2009-02-06 12:26:31

Author: johnmaddock
Date: 2009-02-06 12:26:30 EST (Fri, 06 Feb 2009)
New Revision: 51059
URL: http://svn.boost.org/trac/boost/changeset/51059

Log:
Fix bug in bessel_jn for n == -1.
Add new test case.
Checked that the other Bessel functions do not have the same issue.
Checked that real-valued -1 argument is fixed OK as well as integer argument.
Fixes #2733.
Text files modified: 
   trunk/boost/math/special_functions/detail/bessel_jn.hpp |    23 +++++++++++++++--------                 
   trunk/libs/math/test/test_bessel_j.cpp                  |     4 +++-                                    
   2 files changed, 18 insertions(+), 9 deletions(-)

Modified: trunk/boost/math/special_functions/detail/bessel_jn.hpp
==============================================================================
--- trunk/boost/math/special_functions/detail/bessel_jn.hpp	(original)
+++ trunk/boost/math/special_functions/detail/bessel_jn.hpp	2009-02-06 12:26:30 EST (Fri, 06 Feb 2009)
@@ -28,14 +28,9 @@
 
     BOOST_MATH_STD_USING
 
-    if (n == 0)
-    {
-        return bessel_j0(x);
-    }
-    if (n == 1)
-    {
-        return bessel_j1(x);
-    }
+    //
+    // Reflection has to come first:
+    //
     if (n < 0)
     {
         factor = (n & 0x1) ? -1 : 1;  // J_{-n}(z) = (-1)^n J_n(z)
@@ -45,12 +40,24 @@
     {
         factor = 1;
     }
+    //
+    // Special cases:
+    //
+    if (n == 0)
+    {
+        return factor * bessel_j0(x);
+    }
+    if (n == 1)
+    {
+        return factor * bessel_j1(x);
+    }
 
     if (x == 0)                             // n >= 2
     {
         return static_cast<T>(0);
     }
 
+    BOOST_ASSERT(n > 1);
     if (n < abs(x))                         // forward recurrence
     {
         prev = bessel_j0(x);

Modified: trunk/libs/math/test/test_bessel_j.cpp
==============================================================================
--- trunk/libs/math/test/test_bessel_j.cpp	(original)
+++ trunk/libs/math/test/test_bessel_j.cpp	2009-02-06 12:26:30 EST (Fri, 06 Feb 2009)
@@ -450,7 +450,9 @@
         SC_(1), SC_(10667654)/(1024*1024), SC_(1.24591331097191900488116495350277530373473085499043086981229e-7),
     };
 
-    static const boost::array<boost::array<T, 3>, 14> jn_data = {
+    static const boost::array<boost::array<T, 3>, 15> jn_data = {
+        // This first one is a modified test case from https://svn.boost.org/trac/boost/ticket/2733
+        SC_(-1), SC_(1.25), SC_(-0.510623260319880467069474837274910375352924050139633057168856),
         SC_(2), SC_(0), SC_(0),
         SC_(2), SC_(1e-02), SC_(1.249989583365885362413250958437642113452e-05),
         SC_(5), SC_(10), SC_(-0.2340615281867936404436949416457777864635),