msvcr120: Add fallback implementation of erf function.

Signed-off-by: Piotr Caban <piotr@codeweavers.com> Signed-off-by: Alexandre Julliard <julliard@winehq.org>

msvcr120: Add fallback implementation of erf function.
e495e25a · Piotr Caban · Alexandre Julliard · ddff85a3 · e495e25a
Commit e495e25a authored Jul 12, 2017 by Piotr Caban Committed by Alexandre Julliard Jul 13, 2017
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math.c dlls/msvcrt/math.c +9 -2

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--- a/dlls/msvcrt/math.c
+++ b/dlls/msvcrt/math.c
@@ -2740,8 +2740,15 @@ double CDECL MSVCR120_erf(double x)
 #ifdef HAVE_ERF
    return erf(x);
 #else
-    FIXME( "not implemented\n" );
-    return 0.0;
+    /* Abramowitz and Stegun approximation, maximum error: 1.5*10^-7 */
+    double t, y;
+    int sign = signbit(x);
+
+    if (sign) x = -x;
+    t = 1 / (1 + 0.3275911 * x);
+    y = ((((1.061405429*t - 1.453152027)*t + 1.421413741)*t - 0.284496736)*t + 0.254829592)*t;
+    y = 1.0 - y*exp(-x*x);
+    return sign ? -y : y;
 #endif
 }