diff options
Diffstat (limited to 'src/math/jn.c')
| -rw-r--r-- | src/math/jn.c | 33 |
1 files changed, 14 insertions, 19 deletions
diff --git a/src/math/jn.c b/src/math/jn.c index 082a17bc..d95af15d 100644 --- a/src/math/jn.c +++ b/src/math/jn.c @@ -37,12 +37,7 @@ #include "libm.h" -static const double -invsqrtpi = 5.64189583547756279280e-01, /* 0x3FE20DD7, 0x50429B6D */ -two = 2.00000000000000000000e+00, /* 0x40000000, 0x00000000 */ -one = 1.00000000000000000000e+00; /* 0x3FF00000, 0x00000000 */ - -static const double zero = 0.00000000000000000000e+00; +static const double invsqrtpi = 5.64189583547756279280e-01; /* 0x3FE20DD7, 0x50429B6D */ double jn(int n, double x) { @@ -69,7 +64,7 @@ double jn(int n, double x) sgn = (n&1)&(hx>>31); /* even n -- 0, odd n -- sign(x) */ x = fabs(x); if ((ix|lx) == 0 || ix >= 0x7ff00000) /* if x is 0 or inf */ - b = zero; + b = 0.0; else if ((double)n <= x) { /* Safe to use J(n+1,x)=2n/x *J(n,x)-J(n-1,x) */ if (ix >= 0x52D00000) { /* x > 2**302 */ @@ -108,11 +103,11 @@ double jn(int n, double x) * J(n,x) = 1/n!*(x/2)^n - ... */ if (n > 33) /* underflow */ - b = zero; + b = 0.0; else { temp = x*0.5; b = temp; - for (a=one,i=2; i<=n; i++) { + for (a=1.0,i=2; i<=n; i++) { a *= (double)i; /* a = n! */ b *= temp; /* b = (x/2)^n */ } @@ -165,10 +160,10 @@ double jn(int n, double x) q1 = tmp; } m = n+n; - for (t=zero, i = 2*(n+k); i>=m; i -= 2) - t = one/(i/x-t); + for (t=0.0, i = 2*(n+k); i>=m; i -= 2) + t = 1.0/(i/x-t); a = t; - b = one; + b = 1.0; /* estimate log((2/x)^n*n!) = n*log(2/x)+n*ln(n) * Hence, if n*(log(2n/x)) > ... * single 8.8722839355e+01 @@ -178,7 +173,7 @@ double jn(int n, double x) * likely underflow to zero */ tmp = n; - v = two/x; + v = 2.0/x; tmp = tmp*log(fabs(v*tmp)); if (tmp < 7.09782712893383973096e+02) { for (i=n-1,di=(double)(i+i); i>0; i--) { @@ -186,7 +181,7 @@ double jn(int n, double x) b *= di; b = b/x - a; a = temp; - di -= two; + di -= 2.0; } } else { for (i=n-1,di=(double)(i+i); i>0; i--) { @@ -194,12 +189,12 @@ double jn(int n, double x) b *= di; b = b/x - a; a = temp; - di -= two; + di -= 2.0; /* scale b to avoid spurious overflow */ if (b > 1e100) { a /= b; t /= b; - b = one; + b = 1.0; } } } @@ -229,9 +224,9 @@ double yn(int n, double x) if ((ix|((uint32_t)(lx|-lx))>>31) > 0x7ff00000) return x+x; if ((ix|lx) == 0) - return -one/zero; + return -1.0/0.0; if (hx < 0) - return zero/zero; + return 0.0/0.0; sign = 1; if (n < 0) { n = -n; @@ -242,7 +237,7 @@ double yn(int n, double x) if (n == 1) return sign*y1(x); if (ix == 0x7ff00000) - return zero; + return 0.0; if (ix >= 0x52D00000) { /* x > 2**302 */ /* (x >> n**2) * Jn(x) = cos(x-(2n+1)*pi/4)*sqrt(2/x*pi) |