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-rw-r--r--libm/double/k0.c333
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diff --git a/libm/double/k0.c b/libm/double/k0.c
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-/* k0.c
- *
- * Modified Bessel function, third kind, order zero
- *
- *
- *
- * SYNOPSIS:
- *
- * double x, y, k0();
- *
- * y = k0( x );
- *
- *
- *
- * DESCRIPTION:
- *
- * Returns modified Bessel function of the third kind
- * of order zero of the argument.
- *
- * The range is partitioned into the two intervals [0,8] and
- * (8, infinity). Chebyshev polynomial expansions are employed
- * in each interval.
- *
- *
- *
- * ACCURACY:
- *
- * Tested at 2000 random points between 0 and 8. Peak absolute
- * error (relative when K0 > 1) was 1.46e-14; rms, 4.26e-15.
- * Relative error:
- * arithmetic domain # trials peak rms
- * DEC 0, 30 3100 1.3e-16 2.1e-17
- * IEEE 0, 30 30000 1.2e-15 1.6e-16
- *
- * ERROR MESSAGES:
- *
- * message condition value returned
- * K0 domain x <= 0 MAXNUM
- *
- */
- /* k0e()
- *
- * Modified Bessel function, third kind, order zero,
- * exponentially scaled
- *
- *
- *
- * SYNOPSIS:
- *
- * double x, y, k0e();
- *
- * y = k0e( x );
- *
- *
- *
- * DESCRIPTION:
- *
- * Returns exponentially scaled modified Bessel function
- * of the third kind of order zero of the argument.
- *
- *
- *
- * ACCURACY:
- *
- * Relative error:
- * arithmetic domain # trials peak rms
- * IEEE 0, 30 30000 1.4e-15 1.4e-16
- * See k0().
- *
- */
-
-/*
-Cephes Math Library Release 2.8: June, 2000
-Copyright 1984, 1987, 2000 by Stephen L. Moshier
-*/
-
-#include <math.h>
-
-/* Chebyshev coefficients for K0(x) + log(x/2) I0(x)
- * in the interval [0,2]. The odd order coefficients are all
- * zero; only the even order coefficients are listed.
- *
- * lim(x->0){ K0(x) + log(x/2) I0(x) } = -EUL.
- */
-
-#ifdef UNK
-static double A[] =
-{
- 1.37446543561352307156E-16,
- 4.25981614279661018399E-14,
- 1.03496952576338420167E-11,
- 1.90451637722020886025E-9,
- 2.53479107902614945675E-7,
- 2.28621210311945178607E-5,
- 1.26461541144692592338E-3,
- 3.59799365153615016266E-2,
- 3.44289899924628486886E-1,
--5.35327393233902768720E-1
-};
-#endif
-
-#ifdef DEC
-static unsigned short A[] = {
-0023036,0073417,0032477,0165673,
-0025077,0154126,0016046,0012517,
-0027066,0011342,0035211,0005041,
-0031002,0160233,0037454,0050224,
-0032610,0012747,0037712,0173741,
-0034277,0144007,0172147,0162375,
-0035645,0140563,0125431,0165626,
-0037023,0057662,0125124,0102051,
-0037660,0043304,0004411,0166707,
-0140011,0005467,0047227,0130370
-};
-#endif
-
-#ifdef IBMPC
-static unsigned short A[] = {
-0xfd77,0xe6a7,0xcee1,0x3ca3,
-0xc2aa,0xc384,0xfb0a,0x3d27,
-0x2144,0x4751,0xc25c,0x3da6,
-0x8a13,0x67e5,0x5c13,0x3e20,
-0x5efc,0xe7f9,0x02bc,0x3e91,
-0xfca0,0xfe8c,0xf900,0x3ef7,
-0x3d73,0x7563,0xb82e,0x3f54,
-0x9085,0x554a,0x6bf6,0x3fa2,
-0x3db9,0x8121,0x08d8,0x3fd6,
-0xf61f,0xe9d2,0x2166,0xbfe1
-};
-#endif
-
-#ifdef MIEEE
-static unsigned short A[] = {
-0x3ca3,0xcee1,0xe6a7,0xfd77,
-0x3d27,0xfb0a,0xc384,0xc2aa,
-0x3da6,0xc25c,0x4751,0x2144,
-0x3e20,0x5c13,0x67e5,0x8a13,
-0x3e91,0x02bc,0xe7f9,0x5efc,
-0x3ef7,0xf900,0xfe8c,0xfca0,
-0x3f54,0xb82e,0x7563,0x3d73,
-0x3fa2,0x6bf6,0x554a,0x9085,
-0x3fd6,0x08d8,0x8121,0x3db9,
-0xbfe1,0x2166,0xe9d2,0xf61f
-};
-#endif
-
-
-
-/* Chebyshev coefficients for exp(x) sqrt(x) K0(x)
- * in the inverted interval [2,infinity].
- *
- * lim(x->inf){ exp(x) sqrt(x) K0(x) } = sqrt(pi/2).
- */
-
-#ifdef UNK
-static double B[] = {
- 5.30043377268626276149E-18,
--1.64758043015242134646E-17,
- 5.21039150503902756861E-17,
--1.67823109680541210385E-16,
- 5.51205597852431940784E-16,
--1.84859337734377901440E-15,
- 6.34007647740507060557E-15,
--2.22751332699166985548E-14,
- 8.03289077536357521100E-14,
--2.98009692317273043925E-13,
- 1.14034058820847496303E-12,
--4.51459788337394416547E-12,
- 1.85594911495471785253E-11,
--7.95748924447710747776E-11,
- 3.57739728140030116597E-10,
--1.69753450938905987466E-9,
- 8.57403401741422608519E-9,
--4.66048989768794782956E-8,
- 2.76681363944501510342E-7,
--1.83175552271911948767E-6,
- 1.39498137188764993662E-5,
--1.28495495816278026384E-4,
- 1.56988388573005337491E-3,
--3.14481013119645005427E-2,
- 2.44030308206595545468E0
-};
-#endif
-
-#ifdef DEC
-static unsigned short B[] = {
-0021703,0106456,0076144,0173406,
-0122227,0173144,0116011,0030033,
-0022560,0044562,0006506,0067642,
-0123101,0076243,0123273,0131013,
-0023436,0157713,0056243,0141331,
-0124005,0032207,0063726,0164664,
-0024344,0066342,0051756,0162300,
-0124710,0121365,0154053,0077022,
-0025264,0161166,0066246,0077420,
-0125647,0141671,0006443,0103212,
-0026240,0076431,0077147,0160445,
-0126636,0153741,0174002,0105031,
-0027243,0040102,0035375,0163073,
-0127656,0176256,0113476,0044653,
-0030304,0125544,0006377,0130104,
-0130751,0047257,0110537,0127324,
-0031423,0046400,0014772,0012164,
-0132110,0025240,0155247,0112570,
-0032624,0105314,0007437,0021574,
-0133365,0155243,0174306,0116506,
-0034152,0004776,0061643,0102504,
-0135006,0136277,0036104,0175023,
-0035715,0142217,0162474,0115022,
-0137000,0147671,0065177,0134356,
-0040434,0026754,0175163,0044070
-};
-#endif
-
-#ifdef IBMPC
-static unsigned short B[] = {
-0x9ee1,0xcf8c,0x71a5,0x3c58,
-0x2603,0x9381,0xfecc,0xbc72,
-0xcdf4,0x41a8,0x092e,0x3c8e,
-0x7641,0x74d7,0x2f94,0xbca8,
-0x785b,0x6b94,0xdbf9,0x3cc3,
-0xdd36,0xecfa,0xa690,0xbce0,
-0xdc98,0x4a7d,0x8d9c,0x3cfc,
-0x6fc2,0xbb05,0x145e,0xbd19,
-0xcfe2,0xcd94,0x9c4e,0x3d36,
-0x70d1,0x21a4,0xf877,0xbd54,
-0xfc25,0x2fcc,0x0fa3,0x3d74,
-0x5143,0x3f00,0xdafc,0xbd93,
-0xbcc7,0x475f,0x6808,0x3db4,
-0xc935,0xd2e7,0xdf95,0xbdd5,
-0xf608,0x819f,0x956c,0x3df8,
-0xf5db,0xf22b,0x29d5,0xbe1d,
-0x428e,0x033f,0x69a0,0x3e42,
-0xf2af,0x1b54,0x0554,0xbe69,
-0xe46f,0x81e3,0x9159,0x3e92,
-0xd3a9,0x7f18,0xbb54,0xbebe,
-0x70a9,0xcc74,0x413f,0x3eed,
-0x9f42,0xe788,0xd797,0xbf20,
-0x9342,0xfca7,0xb891,0x3f59,
-0xf71e,0x2d4f,0x19f7,0xbfa0,
-0x6907,0x9f4e,0x85bd,0x4003
-};
-#endif
-
-#ifdef MIEEE
-static unsigned short B[] = {
-0x3c58,0x71a5,0xcf8c,0x9ee1,
-0xbc72,0xfecc,0x9381,0x2603,
-0x3c8e,0x092e,0x41a8,0xcdf4,
-0xbca8,0x2f94,0x74d7,0x7641,
-0x3cc3,0xdbf9,0x6b94,0x785b,
-0xbce0,0xa690,0xecfa,0xdd36,
-0x3cfc,0x8d9c,0x4a7d,0xdc98,
-0xbd19,0x145e,0xbb05,0x6fc2,
-0x3d36,0x9c4e,0xcd94,0xcfe2,
-0xbd54,0xf877,0x21a4,0x70d1,
-0x3d74,0x0fa3,0x2fcc,0xfc25,
-0xbd93,0xdafc,0x3f00,0x5143,
-0x3db4,0x6808,0x475f,0xbcc7,
-0xbdd5,0xdf95,0xd2e7,0xc935,
-0x3df8,0x956c,0x819f,0xf608,
-0xbe1d,0x29d5,0xf22b,0xf5db,
-0x3e42,0x69a0,0x033f,0x428e,
-0xbe69,0x0554,0x1b54,0xf2af,
-0x3e92,0x9159,0x81e3,0xe46f,
-0xbebe,0xbb54,0x7f18,0xd3a9,
-0x3eed,0x413f,0xcc74,0x70a9,
-0xbf20,0xd797,0xe788,0x9f42,
-0x3f59,0xb891,0xfca7,0x9342,
-0xbfa0,0x19f7,0x2d4f,0xf71e,
-0x4003,0x85bd,0x9f4e,0x6907
-};
-#endif
-
-/* k0.c */
-#ifdef ANSIPROT
-extern double chbevl ( double, void *, int );
-extern double exp ( double );
-extern double i0 ( double );
-extern double log ( double );
-extern double sqrt ( double );
-#else
-double chbevl(), exp(), i0(), log(), sqrt();
-#endif
-extern double PI;
-extern double MAXNUM;
-
-double k0(x)
-double x;
-{
-double y, z;
-
-if( x <= 0.0 )
- {
- mtherr( "k0", DOMAIN );
- return( MAXNUM );
- }
-
-if( x <= 2.0 )
- {
- y = x * x - 2.0;
- y = chbevl( y, A, 10 ) - log( 0.5 * x ) * i0(x);
- return( y );
- }
-z = 8.0/x - 2.0;
-y = exp(-x) * chbevl( z, B, 25 ) / sqrt(x);
-return(y);
-}
-
-
-
-
-double k0e( x )
-double x;
-{
-double y;
-
-if( x <= 0.0 )
- {
- mtherr( "k0e", DOMAIN );
- return( MAXNUM );
- }
-
-if( x <= 2.0 )
- {
- y = x * x - 2.0;
- y = chbevl( y, A, 10 ) - log( 0.5 * x ) * i0(x);
- return( y * exp(x) );
- }
-
-y = chbevl( 8.0/x - 2.0, B, 25 ) / sqrt(x);
-return(y);
-}