Raymond Toy pushed to branch master at cmucl / cmucl Commits: 4660c011 by Raymond Toy at 2025-08-14T07:40:17-07:00 Fix #424: Use fdlibm hypot - - - - - 6a2028c5 by Raymond Toy at 2025-08-14T07:40:17-07:00 Merge branch 'issue-424-fix-hypot' into 'master' Fix #424: Use fdlibm hypot Closes #424 See merge request cmucl/cmucl!311 - - - - - 4 changed files: - src/code/irrat.lisp - src/lisp/GNUmakefile - + src/lisp/e_hypot.c - tests/irrat.lisp Changes: ===================================== src/code/irrat.lisp ===================================== @@ -87,7 +87,7 @@ (def-math-rtn ("__ieee754_pow" %pow) 2) #-(or x86 sparc-v7 sparc-v8 sparc-v9) (def-math-rtn "sqrt" 1) -(def-math-rtn "hypot" 2) +(def-math-rtn ("__ieee754_hypot" %hypot) 2) (def-math-rtn ("fdlibm_log1p" %log1p) 1) (def-math-rtn ("fdlibm_expm1" %expm1) 1) ===================================== src/lisp/GNUmakefile ===================================== @@ -28,6 +28,7 @@ FDLIBM = k_sin.c k_cos.c k_tan.c s_sin.c s_cos.c s_tan.c sincos.c \ e_rem_pio2.c k_rem_pio2.c \ e_log10.c s_scalbn.c \ setexception.c \ + e_hypot.c \ log2.c SRCS = lisp.c coreparse.c alloc.c monitor.c print.c interr.c \ ===================================== src/lisp/e_hypot.c ===================================== @@ -0,0 +1,144 @@ + +/* @(#)e_hypot.c 1.3 95/01/18 */ +/* + * ==================================================== + * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. + * + * Developed at SunSoft, a Sun Microsystems, Inc. business. + * Permission to use, copy, modify, and distribute this + * software is freely granted, provided that this notice + * is preserved. + * ==================================================== + */ + +/* __ieee754_hypot(x,y) + * + * Method : + * If (assume round-to-nearest) z=x*x+y*y + * has error less than sqrt(2)/2 ulp, than + * sqrt(z) has error less than 1 ulp (exercise). + * + * So, compute sqrt(x*x+y*y) with some care as + * follows to get the error below 1 ulp: + * + * Assume x>y>0; + * (if possible, set rounding to round-to-nearest) + * 1. if x > 2y use + * x1*x1+(y*y+(x2*(x+x1))) for x*x+y*y + * where x1 = x with lower 32 bits cleared, x2 = x-x1; else + * 2. if x <= 2y use + * t1*y1+((x-y)*(x-y)+(t1*y2+t2*y)) + * where t1 = 2x with lower 32 bits cleared, t2 = 2x-t1, + * y1= y with lower 32 bits chopped, y2 = y-y1. + * + * NOTE: scaling may be necessary if some argument is too + * large or too tiny + * + * Special cases: + * hypot(x,y) is INF if x or y is +INF or -INF; else + * hypot(x,y) is NAN if x or y is NAN. + * + * Accuracy: + * hypot(x,y) returns sqrt(x^2+y^2) with error less + * than 1 ulps (units in the last place) + */ + +#include "fdlibm.h" + +static inline void +set_hiword(double* d, int hi) +{ + union { int i[2]; double d; } ux; + + ux.d = *d; + ux.i[HIWORD] = hi; + *d = ux.d; +} + +static inline int +get_loword(double d) +{ + union { int i[2]; double d; } ux; + ux.d = d; + return ux.i[LOWORD]; +} + +static inline int +get_hiword(double d) +{ + union { int i[2]; double d; } ux; + ux.d = d; + + return ux.i[HIWORD]; +} + + +#ifdef __STDC__ + double __ieee754_hypot(double x, double y) +#else + double __ieee754_hypot(x,y) + double x, y; +#endif +{ + double a=x,b=y,t1,t2,y1,y2,w; + int j,k,ha,hb; + + ha = get_hiword(x)&0x7fffffff; /* high word of x */ + hb = get_hiword(y)&0x7fffffff; /* high word of y */ + if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;} + set_hiword(&a,ha); /* a <- |a| */ + set_hiword(&b, hb); /* b <- |b| */ + + if((ha-hb)>0x3c00000) {return a+b;} /* x/y > 2**60 */ + k=0; + if(ha > 0x5f300000) { /* a>2**500 */ + if(ha >= 0x7ff00000) { /* Inf or NaN */ + w = a+b; /* for sNaN */ + if(((ha&0xfffff)|get_loword(a))==0) w = a; + if(((hb^0x7ff00000)|get_loword(b))==0) w = b; + return w; + } + /* scale a and b by 2**-600 */ + ha -= 0x25800000; hb -= 0x25800000; k += 600; + set_hiword(&a, ha); + set_hiword(&b, hb); + } + if(hb < 0x20b00000) { /* b < 2**-500 */ + if(hb <= 0x000fffff) { /* subnormal b or 0 */ + if((hb|(get_loword(b)))==0) return a; + t1=0; + set_hiword(&t1, 0x7fd00000); /* t1=2^1022 */ + b *= t1; + a *= t1; + k -= 1022; + } else { /* scale a and b by 2^600 */ + ha += 0x25800000; /* a *= 2^600 */ + hb += 0x25800000; /* b *= 2^600 */ + k -= 600; + set_hiword(&a, ha); + set_hiword(&b, hb); + } + } + /* medium size a and b */ + w = a-b; + if (w>b) { + t1 = 0; + set_hiword(&t1, ha); + t2 = a-t1; + w = sqrt(t1*t1-(b*(-b)-t2*(a+t1))); + } else { + a = a+a; + y1 = 0; + set_hiword(&y1, hb); + y2 = b - y1; + t1 = 0; + set_hiword(&t1, ha+0x00100000); + t2 = a - t1; + w = sqrt(t1*y1-(w*(-w)-(t1*y2+t2*b))); + } + if(k!=0) { + t1 = 1.0; + set_hiword(&t1, get_hiword(t1) + (k<<20)); + return t1*w; + } else return w; +} ===================================== tests/irrat.lisp ===================================== @@ -245,3 +245,13 @@ (tanh #c(200w0 200w0)))) +;; See bug #424 +(define-test hypot + (:tag :issues) + (assert-eql 3.8950612975366328d0 + (kernel:%hypot 2.302585092994046d0 3.141592653589793d0)) + (let ((result (expt #C(2.302585092994046d0 3.141592653589793d0) 4))) + (assert-eql -188.4466069439329d0 + (realpart result)) + (assert-eql -132.16721026205448d0 + (imagpart result)))) View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/compare/9a8fd3c477f3bbfa1dec824... -- View it on GitLab: https://gitlab.common-lisp.net/cmucl/cmucl/-/compare/9a8fd3c477f3bbfa1dec824... 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