added errf.c function c code

Added erff.c data file error function data file for testing Added erff.c function Added erff.c function Added erff.c function Removing erff(x) and adding erf(x) Removing erff(x) and adding erf(x) Removing erff(x) and adding erf(x) parallella code Removing erff(x) and adding erf(x) Update Makefile.am Update p_erff_f32.dat Removing erff(x) and adding erf(x) Rename p_erff_f32.dat to p_erf_f32.dat Update p_erf_f32.dat Update Makefile.am Update Makefile.am Rename p_erff.c to p_erf.c Update Makefile.am Update Makefile.am Update Makefile.am Update Makefile.am math: p_erf: Implement error function math: p_erf: Implement error function update erf.c Developer Certificate of Origin Version 1.1 Copyright (C) 2004, 2006 The Linux Foundation and its contributors. 660 York Street, Suite 102, San Francisco, CA 94110 USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Developer's Certificate of Origin 1.1 By making a contribution to this project, I certify that: (a) The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; or (b) The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate open source license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the same open source license (unless I am permitted to submit under a different license), as indicated in the file; or (c) The contribution was provided directly to me by some other person who certified (a), (b) or (c) and I have not modified it. (d) I understand and agree that this project and the contribution are public and that a record of the contribution (including all personal information I submit with it, including my sign-off) is maintained indefinitely and may be redistributed consistent with this project or the open source license(s) involved. Signed-off-by: Adam Szewczyk <[email protected]>
parallella · Jul 28, 2015 · 6fe1782 · 6fe1782
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diff --git a/README.md b/README.md
@@ -214,6 +214,7 @@ FUNCTION     | NOTES
 [p_cosh()](src/math/p_cosh.c)         | hyperbolic cosine  
 [p_div()](src/math/p_div.c)           | division  
 [p_dot()](src/math/p_dot.c)           | dot product  
+[p_erf()](src/math/p_erf.c)           | error function
 [p_exp()](src/math/p_exp.c)           | exponential
 [p_ftoi()](src/math/p_ftoi.c)         | float to  
 [p_itof()](src/math/p_itof.c)         | integer to float conversion  

diff --git a/include/pal_math.h b/include/pal_math.h
@@ -142,6 +142,9 @@ void p_cosh_f32(const float *a, float *c, int n);
 /*division: c =  a ./ b */
 void p_div_f32(const float *a, const float *b, float *c, int n);
 
+/*error function: c = erf ( a ) */
+void p_erf_f32(const float *a, float *c, int n);
+
 /*exponential: c = exp ( a ) */
 void p_exp_f32(const float *a, float *c, int n);
 

diff --git a/src/math/Makefile.am b/src/math/Makefile.am
@@ -20,7 +20,7 @@ libpal_math_la_SOURCES = \
     p_cosh.c \
     p_div.c \
     p_dot.c \
-    p_erff.c \
+    p_erf.c \
     p_exp.c p_exp.h \
     p_ftoi.c \
     p_inv.c \

diff --git a/src/math/p_erf.c b/src/math/p_erf.c
@@ -0,0 +1,46 @@
+#include <pal.h>
+/**
+*
+* Calculate error function
+*
+* @param a     Pointer to input vector
+*
+* @param c     Pointer to output vector
+*
+* @param n     Size of 'a' and 'c' vector.
+*
+* @return      None
+*
+*/
+
+void p_erf_f32(const float *a, float *c, int n)
+
+{ 
+    int i; int sign; float x;
+    for ( i = 0; i < n; i++)
+      { 
+       const float *pa = (a+i); 
+             float *pc = (c+i);
+
+       // the computation is based on formula 7.1.28 from Abramowitz and Stegun for a >= 0
+
+       if (*pa >= 0) sign = 1.0; else sign = -1.0;       // store sign of input variable
+       if (*pa < 0) x = *pa * (-1.0f); else x = *pa;     // this is equivalent of x=abs(a)
+       if (x >= 3.6f) *pc = 1.0f * sign;                 // c = 1 * sign if a >=3.6 else calculate error function
+       else
+	{
+        // constants for formula 7.1.28 from Abramowitz and Stegun
+        float a1 =  0.0705230784f;
+        float a2 =  0.0422820123f;
+        float a3 =  0.0092705272f;
+        float a4 =  0.0001520143f;
+        float a5 =  0.0002765672f;
+        float a6 =  0.0000430638f;
+
+        //formula 7.1.28 from Abramowitz and Stegun
+        float t = 1.0f / ((((((a6 * x + a5) * x + a4) * x + a3) * x + a2) * x + a1) * x + 1.0f);
+        float z = 1.0f - (t * t * t * t * t * t * t * t * t * t * t * t * t * t * t * t) ;
+        *pc = z*sign;
+        }
+      }
+}
diff --git a/tests/math/Makefile.am b/tests/math/Makefile.am
@@ -32,6 +32,7 @@ BUILT_SOURCES = \
     gold/p_cosh_f32.gold.h \
     gold/p_div_f32.gold.h \
     gold/p_dot_f32.gold.h \
+    gold/p_erf_f32.gold.h \
     gold/p_exp_f32.gold.h \
     gold/p_invcbrt_f32.gold.h \
     gold/p_inv_f32.gold.h \
@@ -85,6 +86,7 @@ check_PROGRAMS = \
 	check_p_cosh_f32 \
 	check_p_div_f32 \
 	check_p_dot_f32 \
+	check_p_erf_f32 \
 	check_p_exp_f32 \
 	check_p_ftoi \
 	check_p_invcbrt_f32 \
@@ -130,6 +132,7 @@ check_p_cos_f32_SOURCES         = $(SIMPLE) p_cos.c
 check_p_cosh_f32_SOURCES        = $(SIMPLE) p_cosh.c
 check_p_div_f32_SOURCES         = $(SIMPLE)
 check_p_dot_f32_SOURCES         = $(SIMPLE)
+check_p_erf_f32_SOURCES         = $(SIMPLE) p_erf.c
 check_p_exp_f32_SOURCES         = $(SIMPLE) p_exp.c
 check_p_ftoi_SOURCES            = notest.c
 check_p_inv_f32_SOURCES         = $(SIMPLE)
@@ -176,6 +179,7 @@ check_p_cos_f32_CFLAGS          = -DFUNCTION=p_cos_f32     -DIS_UNARY
 check_p_cosh_f32_CFLAGS         = -DFUNCTION=p_cosh_f32    -DIS_UNARY
 check_p_div_f32_CFLAGS          = -DFUNCTION=p_div_f32     -DIS_BINARY
 check_p_dot_f32_CFLAGS          = -DFUNCTION=p_dot_f32     -DIS_BINARY -DSCALAR_OUTPUT
+check_p_erf_f32_CFLAGS          = -DFUNCTION=p_erf_f32     -DIS_UNARY
 check_p_exp_f32_CFLAGS          = -DFUNCTION=p_exp_f32     -DIS_UNARY
 check_p_ftoi_CFLAGS             = -DFUNCTION=p_ftoi
 check_p_invcbrt_f32_CFLAGS      = -DFUNCTION=p_invcbrt_f32 -DIS_UNARY

diff --git a/tests/math/gold/p_erf_f32.dat b/tests/math/gold/p_erf_f32.dat
@@ -0,0 +1,100 @@
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diff --git a/tests/math/p_erf.c b/tests/math/p_erf.c
@@ -0,0 +1,10 @@
+#include <math.h>
+#include "simple.h"
+
+void generate_ref(float *out, size_t n)
+{
+    size_t i;
+
+    for (i = 0; i < n; i++)
+        out[i] = erff(ai[i]);
+}