From f7dd27a92827af91aa52c78bfbf96d5f7e73c4bd Mon Sep 17 00:00:00 2001 From: Xuejie Xiao Date: Mon, 19 Nov 2012 15:13:18 -0500 Subject: [PATCH] Fix provided implementation of erf and erfc functions. --- src/math.c | 5 +++-- test/t/math.rb | 8 ++++++-- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/src/math.c b/src/math.c index 9aae87acde..3e45509469 100644 --- a/src/math.c +++ b/src/math.c @@ -51,7 +51,7 @@ erf(double x) term *= xsqr/j; sum += term/(2*j+1); ++j; - } while (fabs(term)/sum > MATH_TOLERANCE); + } while (fabs(term/sum) > MATH_TOLERANCE); return two_sqrtpi*sum; } @@ -64,7 +64,8 @@ erfc(double x) double b = x; double c = x; double d = x*x+0.5; - double q1, q2; + double q1; + double q2 = b/d; double n = 1.0; double t; if (fabs(x) < 2.2) { diff --git a/test/t/math.rb b/test/t/math.rb index d71e44fc9a..e582c0166f 100644 --- a/test/t/math.rb +++ b/test/t/math.rb @@ -110,8 +110,12 @@ check_float(Math.erf(1), 0.842700792949715) end - assert('Math.erfc 1') do - check_float(Math.erfc(1), 0.157299207050285) + assert('Math.erf -1') do + check_float(Math.erf(-1), -0.8427007929497148) + end + + assert('Math.erfc -1') do + check_float(Math.erfc(-1), 1.8427007929497148) end end