/* e_j0f.c -- float version of e_j0.c. * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com. */ /* * ==================================================== * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this * software is freely granted, provided that this notice * is preserved. * ==================================================== */ /* * See e_j0.c for complete comments. */ #include "math.h" #include "math_private.h" static __inline float pzerof(float), qzerof(float); static const volatile float vone = 1, vzero = 0; static const float huge = 1e30, one = 1.0, invsqrtpi= 5.6418961287e-01, /* 0x3f106ebb */ tpi = 6.3661974669e-01, /* 0x3f22f983 */ /* R0/S0 on [0, 2.00] */ R02 = 1.5625000000e-02, /* 0x3c800000 */ R03 = -1.8997929874e-04, /* 0xb947352e */ R04 = 1.8295404516e-06, /* 0x35f58e88 */ R05 = -4.6183270541e-09, /* 0xb19eaf3c */ S01 = 1.5619102865e-02, /* 0x3c7fe744 */ S02 = 1.1692678527e-04, /* 0x38f53697 */ S03 = 5.1354652442e-07, /* 0x3509daa6 */ S04 = 1.1661400734e-09; /* 0x30a045e8 */ static const float zero = 0, qrtr = 0.25; float j0f(float x) { float z, s,c,ss,cc,r,u,v; int32_t hx,ix; GET_FLOAT_WORD(hx,x); ix = hx&0x7fffffff; if(ix>=0x7f800000) return one/(x*x); x = fabsf(x); if(ix >= 0x40000000) { /* |x| >= 2.0 */ sincosf(x, &s, &c); ss = s-c; cc = s+c; if(ix<0x7f000000) { /* Make sure x+x does not overflow. */ z = -cosf(x+x); if ((s*c)0x58000000) z = (invsqrtpi*cc)/sqrtf(x); /* |x|>2**49 */ else { u = pzerof(x); v = qzerof(x); z = invsqrtpi*(u*cc-v*ss)/sqrtf(x); } return z; } if(ix<0x3b000000) { /* |x| < 2**-9 */ if(huge+x>one) { /* raise inexact if x != 0 */ if(ix<0x39800000) return one; /* |x|<2**-12 */ else return one - x*x/4; } } z = x*x; r = z*(R02+z*(R03+z*(R04+z*R05))); s = one+z*(S01+z*(S02+z*(S03+z*S04))); if(ix < 0x3F800000) { /* |x| < 1.00 */ return one + z*((r/s)-qrtr); } else { u = x/2; return((one+u)*(one-u)+z*(r/s)); } } static const float u00 = -7.3804296553e-02, /* 0xbd9726b5 */ u01 = 1.7666645348e-01, /* 0x3e34e80d */ u02 = -1.3818567619e-02, /* 0xbc626746 */ u03 = 3.4745343146e-04, /* 0x39b62a69 */ u04 = -3.8140706238e-06, /* 0xb67ff53c */ u05 = 1.9559013964e-08, /* 0x32a802ba */ u06 = -3.9820518410e-11, /* 0xae2f21eb */ v01 = 1.2730483897e-02, /* 0x3c509385 */ v02 = 7.6006865129e-05, /* 0x389f65e0 */ v03 = 2.5915085189e-07, /* 0x348b216c */ v04 = 4.4111031494e-10; /* 0x2ff280c2 */ float y0f(float x) { float z, s,c,ss,cc,u,v; int32_t hx,ix; GET_FLOAT_WORD(hx,x); ix = 0x7fffffff&hx; if(ix>=0x7f800000) return vone/(x+x*x); if(ix==0) return -one/vzero; if(hx<0) return vzero/vzero; if(ix >= 0x40000000) { /* |x| >= 2.0 */ /* y0(x) = sqrt(2/(pi*x))*(p0(x)*sin(x0)+q0(x)*cos(x0)) * where x0 = x-pi/4 * Better formula: * cos(x0) = cos(x)cos(pi/4)+sin(x)sin(pi/4) * = 1/sqrt(2) * (sin(x) + cos(x)) * sin(x0) = sin(x)cos(3pi/4)-cos(x)sin(3pi/4) * = 1/sqrt(2) * (sin(x) - cos(x)) * To avoid cancellation, use * sin(x) +- cos(x) = -cos(2x)/(sin(x) -+ cos(x)) * to compute the worse one. */ sincosf(x, &s, &c); ss = s-c; cc = s+c; /* * j0(x) = 1/sqrt(pi) * (P(0,x)*cc - Q(0,x)*ss) / sqrt(x) * y0(x) = 1/sqrt(pi) * (P(0,x)*ss + Q(0,x)*cc) / sqrt(x) */ if(ix<0x7f000000) { /* make sure x+x not overflow */ z = -cosf(x+x); if ((s*c)0x58000000) z = (invsqrtpi*ss)/sqrtf(x); /* |x|>2**49 */ else { u = pzerof(x); v = qzerof(x); z = invsqrtpi*(u*ss+v*cc)/sqrtf(x); } return z; } if(ix<=0x39000000) { /* x < 2**-13 */ return(u00 + tpi*logf(x)); } z = x*x; u = u00+z*(u01+z*(u02+z*(u03+z*(u04+z*(u05+z*u06))))); v = one+z*(v01+z*(v02+z*(v03+z*v04))); return(u/v + tpi*(j0f(x)*logf(x))); } /* The asymptotic expansions of pzero is * 1 - 9/128 s^2 + 11025/98304 s^4 - ..., where s = 1/x. * For x >= 2, We approximate pzero by * pzero(x) = 1 + (R/S) * where R = pR0 + pR1*s^2 + pR2*s^4 + ... + pR5*s^10 * S = 1 + pS0*s^2 + ... + pS4*s^10 * and * | pzero(x)-1-R/S | <= 2 ** ( -60.26) */ static const float pR8[6] = { /* for x in [inf, 8]=1/[0,0.125] */ 0.0000000000e+00, /* 0x00000000 */ -7.0312500000e-02, /* 0xbd900000 */ -8.0816707611e+00, /* 0xc1014e86 */ -2.5706311035e+02, /* 0xc3808814 */ -2.4852163086e+03, /* 0xc51b5376 */ -5.2530439453e+03, /* 0xc5a4285a */ }; static const float pS8[5] = { 1.1653436279e+02, /* 0x42e91198 */ 3.8337448730e+03, /* 0x456f9beb */ 4.0597855469e+04, /* 0x471e95db */ 1.1675296875e+05, /* 0x47e4087c */ 4.7627726562e+04, /* 0x473a0bba */ }; static const float pR5[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */ -1.1412546255e-11, /* 0xad48c58a */ -7.0312492549e-02, /* 0xbd8fffff */ -4.1596107483e+00, /* 0xc0851b88 */ -6.7674766541e+01, /* 0xc287597b */ -3.3123129272e+02, /* 0xc3a59d9b */ -3.4643338013e+02, /* 0xc3ad3779 */ }; static const float pS5[5] = { 6.0753936768e+01, /* 0x42730408 */ 1.0512523193e+03, /* 0x44836813 */ 5.9789707031e+03, /* 0x45bad7c4 */ 9.6254453125e+03, /* 0x461665c8 */ 2.4060581055e+03, /* 0x451660ee */ }; static const float pR3[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */ -2.5470459075e-09, /* 0xb12f081b */ -7.0311963558e-02, /* 0xbd8fffb8 */ -2.4090321064e+00, /* 0xc01a2d95 */ -2.1965976715e+01, /* 0xc1afba52 */ -5.8079170227e+01, /* 0xc2685112 */ -3.1447946548e+01, /* 0xc1fb9565 */ }; static const float pS3[5] = { 3.5856033325e+01, /* 0x420f6c94 */ 3.6151397705e+02, /* 0x43b4c1ca */ 1.1936077881e+03, /* 0x44953373 */ 1.1279968262e+03, /* 0x448cffe6 */ 1.7358093262e+02, /* 0x432d94b8 */ }; static const float pR2[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */ -8.8753431271e-08, /* 0xb3be98b7 */ -7.0303097367e-02, /* 0xbd8ffb12 */ -1.4507384300e+00, /* 0xbfb9b1cc */ -7.6356959343e+00, /* 0xc0f4579f */ -1.1193166733e+01, /* 0xc1331736 */ -3.2336456776e+00, /* 0xc04ef40d */ }; static const float pS2[5] = { 2.2220300674e+01, /* 0x41b1c32d */ 1.3620678711e+02, /* 0x430834f0 */ 2.7047027588e+02, /* 0x43873c32 */ 1.5387539673e+02, /* 0x4319e01a */ 1.4657617569e+01, /* 0x416a859a */ }; static __inline float pzerof(float x) { const float *p,*q; float z,r,s; int32_t ix; GET_FLOAT_WORD(ix,x); ix &= 0x7fffffff; if(ix>=0x41000000) {p = pR8; q= pS8;} else if(ix>=0x409173eb){p = pR5; q= pS5;} else if(ix>=0x4036d917){p = pR3; q= pS3;} else {p = pR2; q= pS2;} /* ix>=0x40000000 */ z = one/(x*x); r = p[0]+z*(p[1]+z*(p[2]+z*(p[3]+z*(p[4]+z*p[5])))); s = one+z*(q[0]+z*(q[1]+z*(q[2]+z*(q[3]+z*q[4])))); return one+ r/s; } /* For x >= 8, the asymptotic expansions of qzero is * -1/8 s + 75/1024 s^3 - ..., where s = 1/x. * We approximate pzero by * qzero(x) = s*(-1.25 + (R/S)) * where R = qR0 + qR1*s^2 + qR2*s^4 + ... + qR5*s^10 * S = 1 + qS0*s^2 + ... + qS5*s^12 * and * | qzero(x)/s +1.25-R/S | <= 2 ** ( -61.22) */ static const float qR8[6] = { /* for x in [inf, 8]=1/[0,0.125] */ 0.0000000000e+00, /* 0x00000000 */ 7.3242187500e-02, /* 0x3d960000 */ 1.1768206596e+01, /* 0x413c4a93 */ 5.5767340088e+02, /* 0x440b6b19 */ 8.8591972656e+03, /* 0x460a6cca */ 3.7014625000e+04, /* 0x471096a0 */ }; static const float qS8[6] = { 1.6377603149e+02, /* 0x4323c6aa */ 8.0983447266e+03, /* 0x45fd12c2 */ 1.4253829688e+05, /* 0x480b3293 */ 8.0330925000e+05, /* 0x49441ed4 */ 8.4050156250e+05, /* 0x494d3359 */ -3.4389928125e+05, /* 0xc8a7eb69 */ }; static const float qR5[6] = { /* for x in [8,4.5454]=1/[0.125,0.22001] */ 1.8408595828e-11, /* 0x2da1ec79 */ 7.3242180049e-02, /* 0x3d95ffff */ 5.8356351852e+00, /* 0x40babd86 */ 1.3511157227e+02, /* 0x43071c90 */ 1.0272437744e+03, /* 0x448067cd */ 1.9899779053e+03, /* 0x44f8bf4b */ }; static const float qS5[6] = { 8.2776611328e+01, /* 0x42a58da0 */ 2.0778142090e+03, /* 0x4501dd07 */ 1.8847289062e+04, /* 0x46933e94 */ 5.6751113281e+04, /* 0x475daf1d */ 3.5976753906e+04, /* 0x470c88c1 */ -5.3543427734e+03, /* 0xc5a752be */ }; static const float qR3[6] = {/* for x in [4.547,2.8571]=1/[0.2199,0.35001] */ 4.3774099900e-09, /* 0x3196681b */ 7.3241114616e-02, /* 0x3d95ff70 */ 3.3442313671e+00, /* 0x405607e3 */ 4.2621845245e+01, /* 0x422a7cc5 */ 1.7080809021e+02, /* 0x432acedf */ 1.6673394775e+02, /* 0x4326bbe4 */ }; static const float qS3[6] = { 4.8758872986e+01, /* 0x42430916 */ 7.0968920898e+02, /* 0x44316c1c */ 3.7041481934e+03, /* 0x4567825f */ 6.4604252930e+03, /* 0x45c9e367 */ 2.5163337402e+03, /* 0x451d4557 */ -1.4924745178e+02, /* 0xc3153f59 */ }; static const float qR2[6] = {/* for x in [2.8570,2]=1/[0.3499,0.5] */ 1.5044444979e-07, /* 0x342189db */ 7.3223426938e-02, /* 0x3d95f62a */ 1.9981917143e+00, /* 0x3fffc4bf */ 1.4495602608e+01, /* 0x4167edfd */ 3.1666231155e+01, /* 0x41fd5471 */ 1.6252708435e+01, /* 0x4182058c */ }; static const float qS2[6] = { 3.0365585327e+01, /* 0x41f2ecb8 */ 2.6934811401e+02, /* 0x4386ac8f */ 8.4478375244e+02, /* 0x44533229 */ 8.8293585205e+02, /* 0x445cbbe5 */ 2.1266638184e+02, /* 0x4354aa98 */ -5.3109550476e+00, /* 0xc0a9f358 */ }; static __inline float qzerof(float x) { static const float eighth = 0.125; const float *p,*q; float s,r,z; int32_t ix; GET_FLOAT_WORD(ix,x); ix &= 0x7fffffff; if(ix>=0x41000000) {p = qR8; q= qS8;} else if(ix>=0x409173eb){p = qR5; q= qS5;} else if(ix>=0x4036d917){p = qR3; q= qS3;} else {p = qR2; q= qS2;} /* ix>=0x40000000 */ z = one/(x*x); r = p[0]+z*(p[1]+z*(p[2]+z*(p[3]+z*(p[4]+z*p[5])))); s = one+z*(q[0]+z*(q[1]+z*(q[2]+z*(q[3]+z*(q[4]+z*q[5]))))); return (r/s-eighth)/x; }