[Beignet] [PATCH 3/6] GBE: fix bug in erf/erfc.
Zhigang Gong
zhigang.gong at intel.com
Tue Nov 4 21:41:13 PST 2014
erf/erfc diverge (instead of converging to 1 or 0) for arguments above
about 2.
This patch is from:
https://bugs.debian.org/cgi-bin/bugreport.cgi?msg=5;filename=Fix-pow-erf-tgamma.patch;att=3;bug=768090
Signed-off-by: Zhigang Gong <zhigang.gong at intel.com>
---
backend/src/libocl/tmpl/ocl_math.tmpl.cl | 288 ++++++++++++++++++++++++++++++-
utests/utest_math_gen.py | 20 +--
2 files changed, 292 insertions(+), 16 deletions(-)
diff --git a/backend/src/libocl/tmpl/ocl_math.tmpl.cl b/backend/src/libocl/tmpl/ocl_math.tmpl.cl
index 8a3dd25..591e5a9 100644
--- a/backend/src/libocl/tmpl/ocl_math.tmpl.cl
+++ b/backend/src/libocl/tmpl/ocl_math.tmpl.cl
@@ -1930,12 +1930,6 @@ OVERLOADABLE float __gen_ocl_internal_atan(float x) {
OVERLOADABLE float __gen_ocl_internal_atanpi(float x) {
return __gen_ocl_internal_atan(x) / M_PI_F;
}
-OVERLOADABLE float __gen_ocl_internal_erf(float x) {
- return M_2_SQRTPI_F * (x - __gen_ocl_pow(x, 3) / 3 + __gen_ocl_pow(x, 5) / 10 - __gen_ocl_pow(x, 7) / 42 + __gen_ocl_pow(x, 9) / 216);
-}
-OVERLOADABLE float __gen_ocl_internal_erfc(float x) {
- return 1 - __gen_ocl_internal_erf(x);
-}
// XXX work-around PTX profile
OVERLOADABLE float sqrt(float x) { return native_sqrt(x); }
@@ -2155,6 +2149,288 @@ OVERLOADABLE float __gen_ocl_internal_exp(float x) {
return y*twom100;
}
}
+
+/* erf,erfc from glibc s_erff.c -- float version of s_erf.c.
+ * Conversion to float by Ian Lance Taylor, Cygnus Support, ian at cygnus.com.
+ */
+
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+INLINE_OVERLOADABLE float __gen_ocl_internal_erf(float x) {
+/*...*/
+const float
+tiny = 1.0e-30,
+half_val= 5.0000000000e-01, /* 0x3F000000 */
+one = 1.0000000000e+00, /* 0x3F800000 */
+two = 2.0000000000e+00, /* 0x40000000 */
+ /* c = (subfloat)0.84506291151 */
+erx = 8.4506291151e-01, /* 0x3f58560b */
+/*
+ * Coefficients for approximation to erf on [0,0.84375]
+ */
+efx = 1.2837916613e-01, /* 0x3e0375d4 */
+efx8= 1.0270333290e+00, /* 0x3f8375d4 */
+pp0 = 1.2837916613e-01, /* 0x3e0375d4 */
+pp1 = -3.2504209876e-01, /* 0xbea66beb */
+pp2 = -2.8481749818e-02, /* 0xbce9528f */
+pp3 = -5.7702702470e-03, /* 0xbbbd1489 */
+pp4 = -2.3763017452e-05, /* 0xb7c756b1 */
+qq1 = 3.9791721106e-01, /* 0x3ecbbbce */
+qq2 = 6.5022252500e-02, /* 0x3d852a63 */
+qq3 = 5.0813062117e-03, /* 0x3ba68116 */
+qq4 = 1.3249473704e-04, /* 0x390aee49 */
+qq5 = -3.9602282413e-06, /* 0xb684e21a */
+/*
+ * Coefficients for approximation to erf in [0.84375,1.25]
+ */
+pa0 = -2.3621185683e-03, /* 0xbb1acdc6 */
+pa1 = 4.1485610604e-01, /* 0x3ed46805 */
+pa2 = -3.7220788002e-01, /* 0xbebe9208 */
+pa3 = 3.1834661961e-01, /* 0x3ea2fe54 */
+pa4 = -1.1089469492e-01, /* 0xbde31cc2 */
+pa5 = 3.5478305072e-02, /* 0x3d1151b3 */
+pa6 = -2.1663755178e-03, /* 0xbb0df9c0 */
+qa1 = 1.0642088205e-01, /* 0x3dd9f331 */
+qa2 = 5.4039794207e-01, /* 0x3f0a5785 */
+qa3 = 7.1828655899e-02, /* 0x3d931ae7 */
+qa4 = 1.2617121637e-01, /* 0x3e013307 */
+qa5 = 1.3637083583e-02, /* 0x3c5f6e13 */
+qa6 = 1.1984500103e-02, /* 0x3c445aa3 */
+ /*
+ * Coefficients for approximation to erfc in [1.25,1/0.35]
+ */ra0 = -9.8649440333e-03, /* 0xbc21a093 */
+ra1 = -6.9385856390e-01, /* 0xbf31a0b7 */
+ra2 = -1.0558626175e+01, /* 0xc128f022 */
+ra3 = -6.2375331879e+01, /* 0xc2798057 */
+ra4 = -1.6239666748e+02, /* 0xc322658c */
+ra5 = -1.8460508728e+02, /* 0xc3389ae7 */
+ra6 = -8.1287437439e+01, /* 0xc2a2932b */
+ra7 = -9.8143291473e+00, /* 0xc11d077e */
+sa1 = 1.9651271820e+01, /* 0x419d35ce */
+sa2 = 1.3765776062e+02, /* 0x4309a863 */
+sa3 = 4.3456588745e+02, /* 0x43d9486f */
+sa4 = 6.4538726807e+02, /* 0x442158c9 */
+sa5 = 4.2900814819e+02, /* 0x43d6810b */
+sa6 = 1.0863500214e+02, /* 0x42d9451f */
+sa7 = 6.5702495575e+00, /* 0x40d23f7c */
+sa8 = -6.0424413532e-02, /* 0xbd777f97 */
+/*
+ * Coefficients for approximation to erfc in [1/.35,28]
+ */
+rb0 = -9.8649431020e-03, /* 0xbc21a092 */
+rb1 = -7.9928326607e-01, /* 0xbf4c9dd4 */
+rb2 = -1.7757955551e+01, /* 0xc18e104b */
+rb3 = -1.6063638306e+02, /* 0xc320a2ea */
+rb4 = -6.3756646729e+02, /* 0xc41f6441 */
+rb5 = -1.0250950928e+03, /* 0xc480230b */
+rb6 = -4.8351919556e+02, /* 0xc3f1c275 */
+sb1 = 3.0338060379e+01, /* 0x41f2b459 */
+sb2 = 3.2579251099e+02, /* 0x43a2e571 */
+sb3 = 1.5367296143e+03, /* 0x44c01759 */
+sb4 = 3.1998581543e+03, /* 0x4547fdbb */
+sb5 = 2.5530502930e+03, /* 0x451f90ce */
+sb6 = 4.7452853394e+02, /* 0x43ed43a7 */
+sb7 = -2.2440952301e+01; /* 0xc1b38712 */
+
+ int hx,ix,i;
+ float R,S,P,Q,s,y,z,r;
+ GEN_OCL_GET_FLOAT_WORD(hx,x);
+ ix = hx&0x7fffffff;
+ if(ix>=0x7f800000) { /* erf(nan)=nan */
+ i = ((unsigned int)hx>>31)<<1;
+ return (float)(1-i)+one/x; /* erf(+-inf)=+-1 */
+ }
+
+ if(ix < 0x3f580000) { /* |x|<0.84375 */
+ if(ix < 0x31800000) { /* |x|<2**-28 */
+ if (ix < 0x04000000)
+ /*avoid underflow */
+ return (float)0.125*((float)8.0*x+efx8*x);
+ return x + efx*x;
+ }
+ z = x*x;
+ r = pp0+z*(pp1+z*(pp2+z*(pp3+z*pp4)));
+ s = one+z*(qq1+z*(qq2+z*(qq3+z*(qq4+z*qq5))));
+ y = r/s;
+ return x + x*y;
+ }
+ if(ix < 0x3fa00000) { /* 0.84375 <= |x| < 1.25 */
+ s = __gen_ocl_internal_fabs(x)-one;
+ P = pa0+s*(pa1+s*(pa2+s*(pa3+s*(pa4+s*(pa5+s*pa6)))));
+ Q = one+s*(qa1+s*(qa2+s*(qa3+s*(qa4+s*(qa5+s*qa6)))));
+ if(hx>=0) return erx + P/Q; else return -erx - P/Q;
+ }
+ if (ix >= 0x40c00000) { /* inf>|x|>=6 */
+ if(hx>=0) return one-tiny; else return tiny-one;
+ }
+ x = __gen_ocl_internal_fabs(x);
+ s = one/(x*x);
+ if(ix< 0x4036DB6E) { /* |x| < 1/0.35 */
+ R=ra0+s*(ra1+s*(ra2+s*(ra3+s*(ra4+s*(
+ ra5+s*(ra6+s*ra7))))));
+ S=one+s*(sa1+s*(sa2+s*(sa3+s*(sa4+s*(
+ sa5+s*(sa6+s*(sa7+s*sa8)))))));
+ } else { /* |x| >= 1/0.35 */
+ R=rb0+s*(rb1+s*(rb2+s*(rb3+s*(rb4+s*(
+ rb5+s*rb6)))));
+ S=one+s*(sb1+s*(sb2+s*(sb3+s*(sb4+s*(
+ sb5+s*(sb6+s*sb7))))));
+ }
+ GEN_OCL_GET_FLOAT_WORD(ix,x);
+ GEN_OCL_SET_FLOAT_WORD(z,ix&0xfffff000);
+ r = __gen_ocl_internal_exp(-z*z-(float)0.5625)*__gen_ocl_internal_exp((z-x)*(z+x)+R/S);
+ if(hx>=0) return one-r/x; else return r/x-one;
+}
+INLINE_OVERLOADABLE float __gen_ocl_internal_erfc(float x) {
+/*...*/
+const float
+tiny = 1.0e-30,
+half_val= 5.0000000000e-01, /* 0x3F000000 */
+one = 1.0000000000e+00, /* 0x3F800000 */
+two = 2.0000000000e+00, /* 0x40000000 */
+ /* c = (subfloat)0.84506291151 */
+erx = 8.4506291151e-01, /* 0x3f58560b */
+/*
+ * Coefficients for approximation to erf on [0,0.84375]
+ */
+efx = 1.2837916613e-01, /* 0x3e0375d4 */
+efx8= 1.0270333290e+00, /* 0x3f8375d4 */
+pp0 = 1.2837916613e-01, /* 0x3e0375d4 */
+pp1 = -3.2504209876e-01, /* 0xbea66beb */
+pp2 = -2.8481749818e-02, /* 0xbce9528f */
+pp3 = -5.7702702470e-03, /* 0xbbbd1489 */
+pp4 = -2.3763017452e-05, /* 0xb7c756b1 */
+qq1 = 3.9791721106e-01, /* 0x3ecbbbce */
+qq2 = 6.5022252500e-02, /* 0x3d852a63 */
+qq3 = 5.0813062117e-03, /* 0x3ba68116 */
+qq4 = 1.3249473704e-04, /* 0x390aee49 */
+qq5 = -3.9602282413e-06, /* 0xb684e21a */
+/*
+ * Coefficients for approximation to erf in [0.84375,1.25]
+ */
+pa0 = -2.3621185683e-03, /* 0xbb1acdc6 */
+pa1 = 4.1485610604e-01, /* 0x3ed46805 */
+pa2 = -3.7220788002e-01, /* 0xbebe9208 */
+pa3 = 3.1834661961e-01, /* 0x3ea2fe54 */
+pa4 = -1.1089469492e-01, /* 0xbde31cc2 */
+pa5 = 3.5478305072e-02, /* 0x3d1151b3 */
+pa6 = -2.1663755178e-03, /* 0xbb0df9c0 */
+qa1 = 1.0642088205e-01, /* 0x3dd9f331 */
+qa2 = 5.4039794207e-01, /* 0x3f0a5785 */
+qa3 = 7.1828655899e-02, /* 0x3d931ae7 */
+qa4 = 1.2617121637e-01, /* 0x3e013307 */
+qa5 = 1.3637083583e-02, /* 0x3c5f6e13 */
+qa6 = 1.1984500103e-02, /* 0x3c445aa3 */
+ /*
+ * Coefficients for approximation to erfc in [1.25,1/0.35]
+ */ra0 = -9.8649440333e-03, /* 0xbc21a093 */
+ra1 = -6.9385856390e-01, /* 0xbf31a0b7 */
+ra2 = -1.0558626175e+01, /* 0xc128f022 */
+ra3 = -6.2375331879e+01, /* 0xc2798057 */
+ra4 = -1.6239666748e+02, /* 0xc322658c */
+ra5 = -1.8460508728e+02, /* 0xc3389ae7 */
+ra6 = -8.1287437439e+01, /* 0xc2a2932b */
+ra7 = -9.8143291473e+00, /* 0xc11d077e */
+sa1 = 1.9651271820e+01, /* 0x419d35ce */
+sa2 = 1.3765776062e+02, /* 0x4309a863 */
+sa3 = 4.3456588745e+02, /* 0x43d9486f */
+sa4 = 6.4538726807e+02, /* 0x442158c9 */
+sa5 = 4.2900814819e+02, /* 0x43d6810b */
+sa6 = 1.0863500214e+02, /* 0x42d9451f */
+sa7 = 6.5702495575e+00, /* 0x40d23f7c */
+sa8 = -6.0424413532e-02, /* 0xbd777f97 */
+/*
+ * Coefficients for approximation to erfc in [1/.35,28]
+ */
+rb0 = -9.8649431020e-03, /* 0xbc21a092 */
+rb1 = -7.9928326607e-01, /* 0xbf4c9dd4 */
+rb2 = -1.7757955551e+01, /* 0xc18e104b */
+rb3 = -1.6063638306e+02, /* 0xc320a2ea */
+rb4 = -6.3756646729e+02, /* 0xc41f6441 */
+rb5 = -1.0250950928e+03, /* 0xc480230b */
+rb6 = -4.8351919556e+02, /* 0xc3f1c275 */
+sb1 = 3.0338060379e+01, /* 0x41f2b459 */
+sb2 = 3.2579251099e+02, /* 0x43a2e571 */
+sb3 = 1.5367296143e+03, /* 0x44c01759 */
+sb4 = 3.1998581543e+03, /* 0x4547fdbb */
+sb5 = 2.5530502930e+03, /* 0x451f90ce */
+sb6 = 4.7452853394e+02, /* 0x43ed43a7 */
+sb7 = -2.2440952301e+01; /* 0xc1b38712 */
+ int hx,ix;
+ float R,S,P,Q,s,y,z,r;
+ GEN_OCL_GET_FLOAT_WORD(hx,x);
+ ix = hx&0x7fffffff;
+ if(ix>=0x7f800000) { /* erfc(nan)=nan */
+ /* erfc(+-inf)=0,2 */
+ return (float)(((unsigned int)hx>>31)<<1)+one/x;
+ }
+
+ if(ix < 0x3f580000) { /* |x|<0.84375 */
+ if(ix < 0x23800000) /* |x|<2**-56 */
+ return one-x;
+ z = x*x;
+ r = pp0+z*(pp1+z*(pp2+z*(pp3+z*pp4)));
+ s = one+z*(qq1+z*(qq2+z*(qq3+z*(qq4+z*qq5))));
+ y = r/s;
+ if(hx < 0x3e800000) { /* x<1/4 */
+ return one-(x+x*y);
+ } else {
+ r = x*y;
+ r += (x-half_val);
+ return half_val - r ;
+ }
+ }
+ if(ix < 0x3fa00000) { /* 0.84375 <= |x| < 1.25 */
+ s = __gen_ocl_internal_fabs(x)-one;
+ P = pa0+s*(pa1+s*(pa2+s*(pa3+s*(pa4+s*(pa5+s*pa6)))));
+ Q = one+s*(qa1+s*(qa2+s*(qa3+s*(qa4+s*(qa5+s*qa6)))));
+ if(hx>=0) {
+ z = one-erx; return z - P/Q;
+ } else {
+ z = erx+P/Q; return one+z;
+ }
+ }
+ if (ix < 0x41e00000) { /* |x|<28 */
+ x = __gen_ocl_internal_fabs(x);
+ s = one/(x*x);
+ if(ix< 0x4036DB6D) { /* |x| < 1/.35 ~ 2.857143*/
+ R=ra0+s*(ra1+s*(ra2+s*(ra3+s*(ra4+s*(
+ ra5+s*(ra6+s*ra7))))));
+ S=one+s*(sa1+s*(sa2+s*(sa3+s*(sa4+s*(
+ sa5+s*(sa6+s*(sa7+s*sa8)))))));
+ } else { /* |x| >= 1/.35 ~ 2.857143 */
+ if(hx<0&&ix>=0x40c00000) return two-tiny;/* x < -6 */
+ R=rb0+s*(rb1+s*(rb2+s*(rb3+s*(rb4+s*(
+ rb5+s*rb6)))));
+ S=one+s*(sb1+s*(sb2+s*(sb3+s*(sb4+s*(
+ sb5+s*(sb6+s*sb7))))));
+ }
+ GEN_OCL_GET_FLOAT_WORD(ix,x);
+ GEN_OCL_SET_FLOAT_WORD(z,ix&0xffffe000);
+ r = __gen_ocl_internal_exp(-z*z-(float)0.5625)*
+ __gen_ocl_internal_exp((z-x)*(z+x)+R/S);
+ if(hx>0) {
+ float ret = r/x;
+ return ret;
+ } else
+ return two-r/x;
+ } else {
+ if(hx>0) {
+ return tiny*tiny;
+ } else
+ return two-tiny;
+ }
+}
+
OVERLOADABLE float __gen_ocl_internal_fmod (float x, float y) {
//return x-y*__gen_ocl_rndz(x/y);
float one = 1.0;
diff --git a/utests/utest_math_gen.py b/utests/utest_math_gen.py
index 30a9b24..75926b6 100755
--- a/utests/utest_math_gen.py
+++ b/utests/utest_math_gen.py
@@ -216,17 +216,17 @@ static float atanpi(float x){
cospi_cpu_func=reduce1+cospi
cospiUtests = func('cospi','cospi',[cospi_input_type],cospi_output_type,[cospi_input_values],'2 * FLT_ULP',cospi_cpu_func)
-# ##### gentype erf(gentype)
-# erf_input_values = base_input_values
-# erf_input_type = ['float','float2','float4','float8','float16']
-# erf_output_type = ['float','float2','float4','float8','float16']
-# erfUtests = func('erf','erf',[erf_input_type],erf_output_type,[erf_input_values],'16 * FLT_ULP')
+ ##### gentype erf(gentype)
+ erf_input_values = base_input_values
+ erf_input_type = ['float','float2','float4','float8','float16']
+ erf_output_type = ['float','float2','float4','float8','float16']
+ erfUtests = func('erf','erf',[erf_input_type],erf_output_type,[erf_input_values],'16 * FLT_ULP')
-# ##### gentype erfc(gentype)
-# erfc_input_values = base_input_values
-# erfc_input_type = ['float','float2','float4','float8','float16']
-# erfc_output_type = ['float','float2','float4','float8','float16']
-# erfcUtests = func('erfc','erfc',[erfc_input_type],erfc_output_type,[erfc_input_values],'16 * FLT_ULP')
+ ##### gentype erfc(gentype)
+ erfc_input_values = base_input_values
+ erfc_input_type = ['float','float2','float4','float8','float16']
+ erfc_output_type = ['float','float2','float4','float8','float16']
+ erfcUtests = func('erfc','erfc',[erfc_input_type],erfc_output_type,[erfc_input_values],'16 * FLT_ULP')
##### gentype exp(gentype x)
exp_input_values = base_input_values
--
1.8.3.2
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