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Diffstat (limited to 'third_party/js-1.7/fdlibm/e_hypot.c')
| -rw-r--r-- | third_party/js-1.7/fdlibm/e_hypot.c | 173 |
1 files changed, 173 insertions, 0 deletions
diff --git a/third_party/js-1.7/fdlibm/e_hypot.c b/third_party/js-1.7/fdlibm/e_hypot.c new file mode 100644 index 0000000..3900230 --- /dev/null +++ b/third_party/js-1.7/fdlibm/e_hypot.c @@ -0,0 +1,173 @@ +/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- + * + * ***** BEGIN LICENSE BLOCK ***** + * Version: MPL 1.1/GPL 2.0/LGPL 2.1 + * + * The contents of this file are subject to the Mozilla Public License Version + * 1.1 (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * http://www.mozilla.org/MPL/ + * + * Software distributed under the License is distributed on an "AS IS" basis, + * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License + * for the specific language governing rights and limitations under the + * License. + * + * The Original Code is Mozilla Communicator client code, released + * March 31, 1998. + * + * The Initial Developer of the Original Code is + * Sun Microsystems, Inc. + * Portions created by the Initial Developer are Copyright (C) 1998 + * the Initial Developer. All Rights Reserved. + * + * Contributor(s): + * + * Alternatively, the contents of this file may be used under the terms of + * either of the GNU General Public License Version 2 or later (the "GPL"), + * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"), + * in which case the provisions of the GPL or the LGPL are applicable instead + * of those above. If you wish to allow use of your version of this file only + * under the terms of either the GPL or the LGPL, and not to allow others to + * use your version of this file under the terms of the MPL, indicate your + * decision by deleting the provisions above and replace them with the notice + * and other provisions required by the GPL or the LGPL. If you do not delete + * the provisions above, a recipient may use your version of this file under + * the terms of any one of the MPL, the GPL or the LGPL. + * + * ***** END LICENSE BLOCK ***** */ + +/* @(#)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" + +#ifdef __STDC__ + double __ieee754_hypot(double x, double y) +#else + double __ieee754_hypot(x,y) + double x, y; +#endif +{ + fd_twoints ux, uy; + double a=x,b=y,t1,t2,y1,y2,w; + int j,k,ha,hb; + + ux.d = x; uy.d = y; + ha = __HI(ux)&0x7fffffff; /* high word of x */ + hb = __HI(uy)&0x7fffffff; /* high word of y */ + if(hb > ha) {a=y;b=x;j=ha; ha=hb;hb=j;} else {a=x;b=y;} + ux.d = a; uy.d = b; + __HI(ux) = ha; /* a <- |a| */ + __HI(uy) = hb; /* b <- |b| */ + a = ux.d; b = uy.d; + 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 */ + ux.d = a; uy.d = b; + if(((ha&0xfffff)|__LO(ux))==0) w = a; + if(((hb^0x7ff00000)|__LO(uy))==0) w = b; + return w; + } + /* scale a and b by 2**-600 */ + ha -= 0x25800000; hb -= 0x25800000; k += 600; + ux.d = a; uy.d = b; + __HI(ux) = ha; + __HI(uy) = hb; + a = ux.d; b = uy.d; + } + if(hb < 0x20b00000) { /* b < 2**-500 */ + if(hb <= 0x000fffff) { /* subnormal b or 0 */ + uy.d = b; + if((hb|(__LO(uy)))==0) return a; + t1=0; + ux.d = t1; + __HI(ux) = 0x7fd00000; /* t1=2^1022 */ + t1 = ux.d; + 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; + ux.d = a; uy.d = b; + __HI(ux) = ha; + __HI(uy) = hb; + a = ux.d; b = uy.d; + } + } + /* medium size a and b */ + w = a-b; + if (w>b) { + t1 = 0; + ux.d = t1; + __HI(ux) = ha; + t1 = ux.d; + t2 = a-t1; + w = fd_sqrt(t1*t1-(b*(-b)-t2*(a+t1))); + } else { + a = a+a; + y1 = 0; + ux.d = y1; + __HI(ux) = hb; + y1 = ux.d; + y2 = b - y1; + t1 = 0; + ux.d = t1; + __HI(ux) = ha+0x00100000; + t1 = ux.d; + t2 = a - t1; + w = fd_sqrt(t1*y1-(w*(-w)-(t1*y2+t2*b))); + } + if(k!=0) { + t1 = 1.0; + ux.d = t1; + __HI(ux) += (k<<20); + t1 = ux.d; + return t1*w; + } else return w; +} |