diff options
author | Eric Andersen <andersen@codepoet.org> | 2001-11-22 14:04:29 +0000 |
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committer | Eric Andersen <andersen@codepoet.org> | 2001-11-22 14:04:29 +0000 |
commit | 7ce331c01ce6eb7b3f5c715a38a24359da9c6ee2 (patch) | |
tree | 3a7e8476e868ae15f4da1b7ce26b2db6f434468c /libm/double/planck.c | |
parent | c117dd5fb183afb1a4790a6f6110d88704be6bf8 (diff) |
Totally rework the math library, this time based on the MacOs X
math library (which is itself based on the math lib from FreeBSD).
-Erik
Diffstat (limited to 'libm/double/planck.c')
-rw-r--r-- | libm/double/planck.c | 223 |
1 files changed, 0 insertions, 223 deletions
diff --git a/libm/double/planck.c b/libm/double/planck.c deleted file mode 100644 index 834c85dff..000000000 --- a/libm/double/planck.c +++ /dev/null @@ -1,223 +0,0 @@ -/* planck.c - * - * Integral of Planck's black body radiation formula - * - * - * - * SYNOPSIS: - * - * double lambda, T, y, plancki(); - * - * y = plancki( lambda, T ); - * - * - * - * DESCRIPTION: - * - * Evaluates the definite integral, from wavelength 0 to lambda, - * of Planck's radiation formula - * -5 - * c1 lambda - * E = ------------------ - * c2/(lambda T) - * e - 1 - * - * Physical constants c1 = 3.7417749e-16 and c2 = 0.01438769 are built in - * to the function program. They are scaled to provide a result - * in watts per square meter. Argument T represents temperature in degrees - * Kelvin; lambda is wavelength in meters. - * - * The integral is expressed in closed form, in terms of polylogarithms - * (see polylog.c). - * - * The total area under the curve is - * (-1/8) (42 zeta(4) - 12 pi^2 zeta(2) + pi^4 ) c1 (T/c2)^4 - * = (pi^4 / 15) c1 (T/c2)^4 - * = 5.6705032e-8 T^4 - * where sigma = 5.6705032e-8 W m^2 K^-4 is the Stefan-Boltzmann constant. - * - * - * ACCURACY: - * - * The left tail of the function experiences some relative error - * amplification in computing the dominant term exp(-c2/(lambda T)). - * For the right-hand tail see planckc, below. - * - * Relative error. - * The domain refers to lambda T / c2. - * arithmetic domain # trials peak rms - * IEEE 0.1, 10 50000 7.1e-15 5.4e-16 - * - */ - - -/* -Cephes Math Library Release 2.8: July, 1999 -Copyright 1999 by Stephen L. Moshier -*/ - -#include <math.h> -#ifdef ANSIPROT -extern double polylog (int, double); -extern double exp (double); -extern double log1p (double); /* log(1+x) */ -extern double expm1 (double); /* exp(x) - 1 */ -double planckc(double, double); -double plancki(double, double); -#else -double polylog(), exp(), log1p(), expm1(); -double planckc(), plancki(); -#endif - -/* NIST value (1999): 2 pi h c^2 = 3.741 7749(22) 10-16 W m2 */ -double planck_c1 = 3.7417749e-16; -/* NIST value (1999): h c / k = 0.014 387 69 m K */ -double planck_c2 = 0.01438769; - - -double -plancki(w, T) - double w, T; -{ - double b, h, y, bw; - - b = T / planck_c2; - bw = b * w; - - if (bw > 0.59375) - { - y = b * b; - h = y * y; - /* Right tail. */ - y = planckc (w, T); - /* pi^4 / 15 */ - y = 6.493939402266829149096 * planck_c1 * h - y; - return y; - } - - h = exp(-planck_c2/(w*T)); - y = 6. * polylog (4, h) * bw; - y = (y + 6. * polylog (3, h)) * bw; - y = (y + 3. * polylog (2, h)) * bw; - y = (y - log1p (-h)) * bw; - h = w * w; - h = h * h; - y = y * (planck_c1 / h); - return y; -} - -/* planckc - * - * Complemented Planck radiation integral - * - * - * - * SYNOPSIS: - * - * double lambda, T, y, planckc(); - * - * y = planckc( lambda, T ); - * - * - * - * DESCRIPTION: - * - * Integral from w to infinity (area under right hand tail) - * of Planck's radiation formula. - * - * The program for large lambda uses an asymptotic series in inverse - * powers of the wavelength. - * - * ACCURACY: - * - * Relative error. - * The domain refers to lambda T / c2. - * arithmetic domain # trials peak rms - * IEEE 0.6, 10 50000 1.1e-15 2.2e-16 - * - */ - -double -planckc (w, T) - double w; - double T; -{ - double b, d, p, u, y; - - b = T / planck_c2; - d = b*w; - if (d <= 0.59375) - { - y = 6.493939402266829149096 * planck_c1 * b*b*b*b; - return (y - plancki(w,T)); - } - u = 1.0/d; - p = u * u; -#if 0 - y = 236364091.*p/365866013534056632601804800000.; - y = (y - 15458917./475677107995483570176000000.)*p; - y = (y + 174611./123104841613737984000000.)*p; - y = (y - 43867./643745871363538944000.)*p; - y = ((y + 3617./1081289781411840000.)*p - 1./5928123801600.)*p; - y = ((y + 691./78460462080000.)*p - 1./2075673600.)*p; - y = ((((y + 1./35481600.)*p - 1.0/544320.)*p + 1.0/6720.)*p - 1./40.)*p; - y = y + log(d * expm1(u)); - y = y - 5.*u/8. + 1./3.; -#else - y = -236364091.*p/45733251691757079075225600000.; - y = (y + 77683./352527500984795136000000.)*p; - y = (y - 174611./18465726242060697600000.)*p; - y = (y + 43867./107290978560589824000.)*p; - y = ((y - 3617./202741834014720000.)*p + 1./1270312243200.)*p; - y = ((y - 691./19615115520000.)*p + 1./622702080.)*p; - y = ((((y - 1./13305600.)*p + 1./272160.)*p - 1./5040.)*p + 1./60.)*p; - y = y - 0.125*u + 1./3.; -#endif - y = y * planck_c1 * b / (w*w*w); - return y; -} - - -/* planckd - * - * Planck's black body radiation formula - * - * - * - * SYNOPSIS: - * - * double lambda, T, y, planckd(); - * - * y = planckd( lambda, T ); - * - * - * - * DESCRIPTION: - * - * Evaluates Planck's radiation formula - * -5 - * c1 lambda - * E = ------------------ - * c2/(lambda T) - * e - 1 - * - */ - -double -planckd(w, T) - double w, T; -{ - return (planck_c2 / ((w*w*w*w*w) * (exp(planck_c2/(w*T)) - 1.0))); -} - - -/* Wavelength, w, of maximum radiation at given temperature T. - c2/wT = constant - Wein displacement law. - */ -double -planckw(T) - double T; -{ - return (planck_c2 / (4.96511423174427630 * T)); -} |