glibc
2.9

Go to the source code of this file.
Functions  
double  fastiroot (double) 
void  __mpsqrt (mp_no *x, mp_no *y, int p) 
Definition at line 46 of file mpsqrt.c.
{ #include "mpsqrt.h" int i,m,ex,ey; double dx,dy; mp_no mphalf = {0,{0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0, 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0, 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0}}, mp3halfs = {0,{0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0, 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0, 0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0,0.0}}; mp_no mpxn,mpz,mpu,mpt1,mpt2; /* Prepare multiprecision 1/2 and 3/2 */ mphalf.e =0; mphalf.d[0] =ONE; mphalf.d[1] =HALFRAD; mp3halfs.e=1; mp3halfs.d[0]=ONE; mp3halfs.d[1]=ONE; mp3halfs.d[2]=HALFRAD; ex=EX; ey=EX/2; __cpy(x,&mpxn,p); mpxn.e = (ey+ey); __mp_dbl(&mpxn,&dx,p); dy=fastiroot(dx); __dbl_mp(dy,&mpu,p); __mul(&mpxn,&mphalf,&mpz,p); m=mp[p]; for (i=0; i<m; i++) { __mul(&mpu,&mpu,&mpt1,p); __mul(&mpt1,&mpz,&mpt2,p); __sub(&mp3halfs,&mpt2,&mpt1,p); __mul(&mpu,&mpt1,&mpt2,p); __cpy(&mpt2,&mpu,p); } __mul(&mpxn,&mpu,y,p); EY += ey; return; }
double fastiroot  (  double  x  ) 
Definition at line 85 of file mpsqrt.c.
{ union {int i[2]; double d;} p,q; double y,z, t; int n; static const double c0 = 0.99674, c1 = 0.53380, c2 = 0.45472, c3 = 0.21553; p.d = x; p.i[HIGH_HALF] = (p.i[HIGH_HALF] & 0x3FFFFFFF )  0x3FE00000 ; q.d = x; y = p.d; z = y 1.0; n = (q.i[HIGH_HALF]  p.i[HIGH_HALF])>>1; z = ((c3*z + c2)*z + c1)*z + c0; /* 2**7 */ z = z*(1.5  0.5*y*z*z); /* 2**14 */ p.d = z*(1.5  0.5*y*z*z); /* 2**28 */ p.i[HIGH_HALF] = n; t = x*p.d; return p.d*(1.5  0.5*p.d*t); }