diff options
Diffstat (limited to 'src/math/pow.c')
| -rw-r--r-- | src/math/pow.c | 37 |
1 files changed, 17 insertions, 20 deletions
diff --git a/src/math/pow.c b/src/math/pow.c index 5bcedd5b..052825a6 100644 --- a/src/math/pow.c +++ b/src/math/pow.c @@ -59,9 +59,6 @@ static const double bp[] = {1.0, 1.5,}, dp_h[] = { 0.0, 5.84962487220764160156e-01,}, /* 0x3FE2B803, 0x40000000 */ dp_l[] = { 0.0, 1.35003920212974897128e-08,}, /* 0x3E4CFDEB, 0x43CFD006 */ -zero = 0.0, -one = 1.0, -two = 2.0, two53 = 9007199254740992.0, /* 0x43400000, 0x00000000 */ huge = 1.0e300, tiny = 1.0e-300, @@ -101,15 +98,15 @@ double pow(double x, double y) ix = hx & 0x7fffffff; iy = hy & 0x7fffffff; - /* y == zero: x**0 = 1 */ + /* y == 0.0: x**0 = 1 */ if ((iy|ly) == 0) - return one; + return 1.0; /* x == 1: 1**y = 1, even if y is NaN */ if (hx == 0x3ff00000 && lx == 0) - return one; + return 1.0; - /* y != zero: result is NaN if either arg is NaN */ + /* y != 0.0: result is NaN if either arg is NaN */ if (ix > 0x7ff00000 || (ix == 0x7ff00000 && lx != 0) || iy > 0x7ff00000 || (iy == 0x7ff00000 && ly != 0)) return (x+0.0) + (y+0.0); @@ -141,15 +138,15 @@ double pow(double x, double y) if (ly == 0) { if (iy == 0x7ff00000) { /* y is +-inf */ if (((ix-0x3ff00000)|lx) == 0) /* (-1)**+-inf is 1 */ - return one; + return 1.0; else if (ix >= 0x3ff00000) /* (|x|>1)**+-inf = inf,0 */ - return hy >= 0 ? y : zero; + return hy >= 0 ? y : 0.0; else /* (|x|<1)**+-inf = 0,inf */ - return hy < 0 ? -y : zero; + return hy < 0 ? -y : 0.0; } if (iy == 0x3ff00000) { /* y is +-1 */ if (hy < 0) - return one/x; + return 1.0/x; return x; } if (hy == 0x40000000) /* y is 2 */ @@ -166,7 +163,7 @@ double pow(double x, double y) if (ix == 0x7ff00000 || ix == 0 || ix == 0x3ff00000) { /* x is +-0,+-inf,+-1 */ z = ax; if (hy < 0) /* z = (1/|x|) */ - z = one/z; + z = 1.0/z; if (hx < 0) { if (((ix-0x3ff00000)|yisint) == 0) { z = (z-z)/(z-z); /* (-1)**non-int is NaN */ @@ -187,9 +184,9 @@ double pow(double x, double y) if ((n|yisint) == 0) return (x-x)/(x-x); - s = one; /* s (sign of result -ve**odd) = -1 else = 1 */ + s = 1.0; /* s (sign of result -ve**odd) = -1 else = 1 */ if ((n|(yisint-1)) == 0) - s = -one;/* (-ve)**(odd int) */ + s = -1.0;/* (-ve)**(odd int) */ /* |y| is huge */ if (iy > 0x41e00000) { /* if |y| > 2**31 */ @@ -206,7 +203,7 @@ double pow(double x, double y) return hy > 0 ? s*huge*huge : s*tiny*tiny; /* now |1-x| is tiny <= 2**-20, suffice to compute log(x) by x-x^2/2+x^3/3-x^4/4 */ - t = ax - one; /* t has 20 trailing zeros */ + t = ax - 1.0; /* t has 20 trailing zeros */ w = (t*t)*(0.5 - t*(0.3333333333333333333333-t*0.25)); u = ivln2_h*t; /* ivln2_h has 21 sig. bits */ v = t*ivln2_l - w*ivln2; @@ -239,12 +236,12 @@ double pow(double x, double y) /* compute ss = s_h+s_l = (x-1)/(x+1) or (x-1.5)/(x+1.5) */ u = ax - bp[k]; /* bp[0]=1.0, bp[1]=1.5 */ - v = one/(ax+bp[k]); + v = 1.0/(ax+bp[k]); ss = u*v; s_h = ss; SET_LOW_WORD(s_h, 0); /* t_h=ax+bp[k] High */ - t_h = zero; + t_h = 0.0; SET_HIGH_WORD(t_h, ((ix>>1)|0x20000000) + 0x00080000 + (k<<18)); t_l = ax - (t_h-bp[k]); s_l = v*((u-s_h*t_h)-s_h*t_l); @@ -299,7 +296,7 @@ double pow(double x, double y) if (i > 0x3fe00000) { /* if |z| > 0.5, set n = [z+0.5] */ n = j + (0x00100000>>(k+1)); k = ((n&0x7fffffff)>>20) - 0x3ff; /* new k for n */ - t = zero; + t = 0.0; SET_HIGH_WORD(t, n & ~(0x000fffff>>k)); n = ((n&0x000fffff)|0x00100000)>>(20-k); if (j < 0) @@ -314,8 +311,8 @@ double pow(double x, double y) w = v - (z-u); t = z*z; t1 = z - t*(P1+t*(P2+t*(P3+t*(P4+t*P5)))); - r = (z*t1)/(t1-two) - (w + z*w); - z = one - (r-z); + r = (z*t1)/(t1-2.0) - (w + z*w); + z = 1.0 - (r-z); GET_HIGH_WORD(j, z); j += n<<20; if ((j>>20) <= 0) /* subnormal output */ |