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math: bessel cleanup (j1.c and j1f.c) 

a common code path in j1 and y1 was factored out so the resulting
object code is a bit smaller

unsigned int arithmetics is used for bit manipulation

j1(-inf) now returns 0 instead of -0

an incorrect threshold in the common code of j1f and y1f got fixed
(this caused spurious overflow and underflow exceptions)

the else branch in pone and pzero functions are fixed
(so code analyzers dont warn about uninitialized values)
rs-1.0
Szabolcs Nagy 14 years ago
parent
697acde67e
commit
5bb6b24952
2 changed files with 138 additions and 187 deletions
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  1. 172
      src/math/j1.c
  2. 153
      src/math/j1f.c

172
src/math/j1.c
View File

@ -59,10 +59,47 @@
static double pone(double), qone(double);
static const double
huge = 1e300,
invsqrtpi = 5.64189583547756279280e-01, /* 0x3FE20DD7, 0x50429B6D */
tpi = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */
tpi = 6.36619772367581382433e-01; /* 0x3FE45F30, 0x6DC9C883 */
static double common(uint32_t ix, double x, int y1, int sign)
{
double z,s,c,ss,cc;
/*
* j1(x) = sqrt(2/(pi*x))*(p1(x)*cos(x-3pi/4)-q1(x)*sin(x-3pi/4))
* y1(x) = sqrt(2/(pi*x))*(p1(x)*sin(x-3pi/4)+q1(x)*cos(x-3pi/4))
*
* sin(x-3pi/4) = -(sin(x) + cos(x))/sqrt(2)
* cos(x-3pi/4) = (sin(x) - cos(x))/sqrt(2)
* sin(x) +- cos(x) = -cos(2x)/(sin(x) -+ cos(x))
*/
s = sin(x);
if (y1)
s = -s;
c = cos(x);
cc = s-c;
if (ix < 0x7fe00000) {
/* avoid overflow in 2*x */
ss = -s-c;
z = cos(2*x);
if (s*c > 0)
cc = z/ss;
else
ss = z/cc;
if (ix < 0x48000000) {
if (y1)
ss = -ss;
cc = pone(x)*cc-qone(x)*ss;
}
}
if (sign)
cc = -cc;
return invsqrtpi*cc/sqrt(x);
}
/* R0/S0 on [0,2] */
static const double
r00 = -6.25000000000000000000e-02, /* 0xBFB00000, 0x00000000 */
r01 = 1.40705666955189706048e-03, /* 0x3F570D9F, 0x98472C61 */
r02 = -1.59955631084035597520e-05, /* 0xBEF0C5C6, 0xBA169668 */
@ -75,52 +112,26 @@ s05 = 1.23542274426137913908e-11; /* 0x3DAB2ACF, 0xCFB97ED8 */
double j1(double x)
{
double z,s,c,ss,cc,r,u,v,y;
int32_t hx,ix;
double z,r,s;
uint32_t ix;
int sign;
GET_HIGH_WORD(hx, x);
ix = hx & 0x7fffffff;
GET_HIGH_WORD(ix, x);
sign = ix>>31;
ix &= 0x7fffffff;
if (ix >= 0x7ff00000)
return 1.0/x;
y = fabs(x);
if (ix >= 0x40000000) { /* |x| >= 2.0 */
s = sin(y);
c = cos(y);
ss = -s-c;
cc = s-c;
if (ix < 0x7fe00000) { /* make sure y+y not overflow */
z = cos(y+y);
if (s*c > 0.0)
cc = z/ss;
else
ss = z/cc;
}
/*
* j1(x) = 1/sqrt(pi) * (P(1,x)*cc - Q(1,x)*ss) / sqrt(x)
* y1(x) = 1/sqrt(pi) * (P(1,x)*ss + Q(1,x)*cc) / sqrt(x)
*/
if (ix > 0x48000000)
z = (invsqrtpi*cc)/sqrt(y);
else {
u = pone(y);
v = qone(y);
z = invsqrtpi*(u*cc-v*ss)/sqrt(y);
}
if (hx < 0)
return -z;
else
return z;
}
if (ix < 0x3e400000) { /* |x| < 2**-27 */
/* raise inexact if x!=0 */
if (huge+x > 1.0)
return 0.5*x;
}
z = x*x;
r = z*(r00+z*(r01+z*(r02+z*r03)));
s = 1.0+z*(s01+z*(s02+z*(s03+z*(s04+z*s05))));
r *= x;
return x*0.5 + r/s;
return 1/(x*x);
if (ix >= 0x40000000) /* |x| >= 2 */
return common(ix, fabs(x), 0, sign);
if (ix >= 0x38000000) { /* |x| >= 2**-127 */
z = x*x;
r = z*(r00+z*(r01+z*(r02+z*r03)));
s = 1+z*(s01+z*(s02+z*(s03+z*(s04+z*s05))));
z = r/s;
} else
/* avoid underflow, raise inexact if x!=0 */
z = x;
return (0.5 + z)*x;
}
static const double U0[5] = {
@ -138,59 +149,28 @@ static const double V0[5] = {
1.66559246207992079114e-11, /* 0x3DB25039, 0xDACA772A */
};
double y1(double x)
{
double z,s,c,ss,cc,u,v;
int32_t hx,ix,lx;
double z,u,v;
uint32_t ix,lx;
EXTRACT_WORDS(hx, lx, x);
ix = 0x7fffffff & hx;
/* if Y1(NaN) is NaN, Y1(-inf) is NaN, Y1(inf) is 0 */
EXTRACT_WORDS(ix, lx, x);
/* y1(nan)=nan, y1(<0)=nan, y1(0)=-inf, y1(inf)=0 */
if ((ix<<1 | lx) == 0)
return -1/0.0;
if (ix>>31)
return 0/0.0;
if (ix >= 0x7ff00000)
return 1.0/(x+x*x);
if ((ix|lx) == 0)
return -1.0/0.0;
if (hx < 0)
return 0.0/0.0;
if (ix >= 0x40000000) { /* |x| >= 2.0 */
s = sin(x);
c = cos(x);
ss = -s-c;
cc = s-c;
if (ix < 0x7fe00000) { /* make sure x+x not overflow */
z = cos(x+x);
if (s*c > 0.0)
cc = z/ss;
else
ss = z/cc;
}
/* y1(x) = sqrt(2/(pi*x))*(p1(x)*sin(x0)+q1(x)*cos(x0))
* where x0 = x-3pi/4
* Better formula:
* cos(x0) = cos(x)cos(3pi/4)+sin(x)sin(3pi/4)
* = 1/sqrt(2) * (sin(x) - cos(x))
* sin(x0) = sin(x)cos(3pi/4)-cos(x)sin(3pi/4)
* = -1/sqrt(2) * (cos(x) + sin(x))
* To avoid cancellation, use
* sin(x) +- cos(x) = -cos(2x)/(sin(x) -+ cos(x))
* to compute the worse one.
*/
if (ix > 0x48000000)
z = (invsqrtpi*ss)/sqrt(x);
else {
u = pone(x);
v = qone(x);
z = invsqrtpi*(u*ss+v*cc)/sqrt(x);
}
return z;
}
if (ix <= 0x3c900000) /* x < 2**-54 */
return 1/x;
if (ix >= 0x40000000) /* x >= 2 */
return common(ix, x, 1, 0);
if (ix < 0x3c900000) /* x < 2**-54 */
return -tpi/x;
z = x*x;
u = U0[0]+z*(U0[1]+z*(U0[2]+z*(U0[3]+z*U0[4])));
v = 1.0+z*(V0[0]+z*(V0[1]+z*(V0[2]+z*(V0[3]+z*V0[4]))));
return x*(u/v) + tpi*(j1(x)*log(x)-1.0/x);
v = 1+z*(V0[0]+z*(V0[1]+z*(V0[2]+z*(V0[3]+z*V0[4]))));
return x*(u/v) + tpi*(j1(x)*log(x)-1/x);
}
/* For x >= 8, the asymptotic expansions of pone is
@ -271,14 +251,14 @@ static double pone(double x)
{
const double *p,*q;
double z,r,s;
int32_t ix;
uint32_t ix;
GET_HIGH_WORD(ix, x);
ix &= 0x7fffffff;
if (ix >= 0x40200000){p = pr8; q = ps8;}
else if (ix >= 0x40122E8B){p = pr5; q = ps5;}
else if (ix >= 0x4006DB6D){p = pr3; q = ps3;}
else if (ix >= 0x40000000){p = pr2; q = ps2;}
else /*ix >= 0x40000000*/ {p = pr2; q = ps2;}
z = 1.0/(x*x);
r = p[0]+z*(p[1]+z*(p[2]+z*(p[3]+z*(p[4]+z*p[5]))));
s = 1.0+z*(q[0]+z*(q[1]+z*(q[2]+z*(q[3]+z*q[4]))));
@ -367,14 +347,14 @@ static double qone(double x)
{
const double *p,*q;
double s,r,z;
int32_t ix;
uint32_t ix;
GET_HIGH_WORD(ix, x);
ix &= 0x7fffffff;
if (ix >= 0x40200000){p = qr8; q = qs8;}
else if (ix >= 0x40122E8B){p = qr5; q = qs5;}
else if (ix >= 0x4006DB6D){p = qr3; q = qs3;}
else if (ix >= 0x40000000){p = qr2; q = qs2;}
else /*ix >= 0x40000000*/ {p = qr2; q = qs2;}
z = 1.0/(x*x);
r = p[0]+z*(p[1]+z*(p[2]+z*(p[3]+z*(p[4]+z*p[5]))));
s = 1.0+z*(q[0]+z*(q[1]+z*(q[2]+z*(q[3]+z*(q[4]+z*q[5])))));

153
src/math/j1f.c
View File

@ -18,10 +18,38 @@
static float ponef(float), qonef(float);
static const float
huge = 1e30,
invsqrtpi = 5.6418961287e-01, /* 0x3f106ebb */
tpi = 6.3661974669e-01, /* 0x3f22f983 */
tpi = 6.3661974669e-01; /* 0x3f22f983 */
static float common(uint32_t ix, float x, int y1, int sign)
{
double z,s,c,ss,cc;
s = sinf(x);
if (y1)
s = -s;
c = cosf(x);
cc = s-c;
if (ix < 0x7f000000) {
ss = -s-c;
z = cosf(2*x);
if (s*c > 0)
cc = z/ss;
else
ss = z/cc;
if (ix < 0x58800000) {
if (y1)
ss = -ss;
cc = ponef(x)*cc-qonef(x)*ss;
}
}
if (sign)
cc = -cc;
return invsqrtpi*cc/sqrtf(x);
}
/* R0/S0 on [0,2] */
static const float
r00 = -6.2500000000e-02, /* 0xbd800000 */
r01 = 1.4070566976e-03, /* 0x3ab86cfd */
r02 = -1.5995563444e-05, /* 0xb7862e36 */
@ -34,51 +62,26 @@ s05 = 1.2354227016e-11; /* 0x2d59567e */
float j1f(float x)
{
float z,s,c,ss,cc,r,u,v,y;
int32_t hx,ix;
float z,r,s;
uint32_t ix;
int sign;
GET_FLOAT_WORD(hx, x);
ix = hx & 0x7fffffff;
GET_FLOAT_WORD(ix, x);
sign = ix>>31;
ix &= 0x7fffffff;
if (ix >= 0x7f800000)
return 1.0f/x;
y = fabsf(x);
if (ix >= 0x40000000) { /* |x| >= 2.0 */
s = sinf(y);
c = cosf(y);
ss = -s-c;
cc = s-c;
if (ix < 0x7f000000) { /* make sure y+y not overflow */
z = cosf(y+y);
if (s*c > 0.0f)
cc = z/ss;
else
ss = z/cc;
}
/*
* j1(x) = 1/sqrt(pi) * (P(1,x)*cc - Q(1,x)*ss) / sqrt(x)
* y1(x) = 1/sqrt(pi) * (P(1,x)*ss + Q(1,x)*cc) / sqrt(x)
*/
if (ix > 0x80000000)
z = (invsqrtpi*cc)/sqrtf(y);
else {
u = ponef(y);
v = qonef(y);
z = invsqrtpi*(u*cc-v*ss)/sqrtf(y);
}
if (hx < 0)
return -z;
return z;
}
if (ix < 0x32000000) { /* |x| < 2**-27 */
return 1/(x*x);
if (ix >= 0x40000000) /* |x| >= 2 */
return common(ix, fabsf(x), 0, sign);
if (ix >= 0x32000000) { /* |x| >= 2**-27 */
z = x*x;
r = z*(r00+z*(r01+z*(r02+z*r03)));
s = 1+z*(s01+z*(s02+z*(s03+z*(s04+z*s05))));
z = 0.5f + r/s;
} else
/* raise inexact if x!=0 */
if (huge+x > 1.0f)
return 0.5f*x;
}
z = x*x;
r = z*(r00+z*(r01+z*(r02+z*r03)));
s = 1.0f+z*(s01+z*(s02+z*(s03+z*(s04+z*s05))));
r *= x;
return 0.5f*x + r/s;
z = 0.5f + x;
return z*x;
}
static const float U0[5] = {
@ -98,51 +101,19 @@ static const float V0[5] = {
float y1f(float x)
{
float z,s,c,ss,cc,u,v;
int32_t hx,ix;
float z,u,v;
uint32_t ix;
GET_FLOAT_WORD(hx, x);
ix = 0x7fffffff & hx;
/* if Y1(NaN) is NaN, Y1(-inf) is NaN, Y1(inf) is 0 */
GET_FLOAT_WORD(ix, x);
if ((ix & 0x7fffffff) == 0)
return -1/0.0f;
if (ix>>31)
return 0/0.0f;
if (ix >= 0x7f800000)
return 1.0f/(x+x*x);
if (ix == 0)
return -1.0f/0.0f;
if (hx < 0)
return 0.0f/0.0f;
if (ix >= 0x40000000) { /* |x| >= 2.0 */
s = sinf(x);
c = cosf(x);
ss = -s-c;
cc = s-c;
if (ix < 0x7f000000) { /* make sure x+x not overflow */
z = cosf(x+x);
if (s*c > 0.0f)
cc = z/ss;
else
ss = z/cc;
}
/* y1(x) = sqrt(2/(pi*x))*(p1(x)*sin(x0)+q1(x)*cos(x0))
* where x0 = x-3pi/4
* Better formula:
* cos(x0) = cos(x)cos(3pi/4)+sin(x)sin(3pi/4)
* = 1/sqrt(2) * (sin(x) - cos(x))
* sin(x0) = sin(x)cos(3pi/4)-cos(x)sin(3pi/4)
* = -1/sqrt(2) * (cos(x) + sin(x))
* To avoid cancellation, use
* sin(x) +- cos(x) = -cos(2x)/(sin(x) -+ cos(x))
* to compute the worse one.
*/
if (ix > 0x48000000)
z = (invsqrtpi*ss)/sqrtf(x);
else {
u = ponef(x);
v = qonef(x);
z = invsqrtpi*(u*ss+v*cc)/sqrtf(x);
}
return z;
}
if (ix <= 0x24800000) /* x < 2**-54 */
return 1/x;
if (ix >= 0x40000000) /* |x| >= 2.0 */
return common(ix,x,1,0);
if (ix < 0x32000000) /* x < 2**-27 */
return -tpi/x;
z = x*x;
u = U0[0]+z*(U0[1]+z*(U0[2]+z*(U0[3]+z*U0[4])));
@ -228,14 +199,14 @@ static float ponef(float x)
{
const float *p,*q;
float z,r,s;
int32_t ix;
uint32_t ix;
GET_FLOAT_WORD(ix, x);
ix &= 0x7fffffff;
if (ix >= 0x41000000){p = pr8; q = ps8;}
else if (ix >= 0x40f71c58){p = pr5; q = ps5;}
else if (ix >= 0x4036db68){p = pr3; q = ps3;}
else if (ix >= 0x40000000){p = pr2; q = ps2;}
else /*ix >= 0x40000000*/ {p = pr2; q = ps2;}
z = 1.0f/(x*x);
r = p[0]+z*(p[1]+z*(p[2]+z*(p[3]+z*(p[4]+z*p[5]))));
s = 1.0f+z*(q[0]+z*(q[1]+z*(q[2]+z*(q[3]+z*q[4]))));
@ -324,14 +295,14 @@ static float qonef(float x)
{
const float *p,*q;
float s,r,z;
int32_t ix;
uint32_t ix;
GET_FLOAT_WORD(ix, x);
ix &= 0x7fffffff;
if (ix >= 0x40200000){p = qr8; q = qs8;}
else if (ix >= 0x40f71c58){p = qr5; q = qs5;}
else if (ix >= 0x4036db68){p = qr3; q = qs3;}
else if (ix >= 0x40000000){p = qr2; q = qs2;}
else /*ix >= 0x40000000*/ {p = qr2; q = qs2;}
z = 1.0f/(x*x);
r = p[0]+z*(p[1]+z*(p[2]+z*(p[3]+z*(p[4]+z*p[5]))));
s = 1.0f+z*(q[0]+z*(q[1]+z*(q[2]+z*(q[3]+z*(q[4]+z*q[5])))));

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