Unused code.
Project: http://git-wip-us.apache.org/repos/asf/commons-rng/repo Commit: http://git-wip-us.apache.org/repos/asf/commons-rng/commit/2753012c Tree: http://git-wip-us.apache.org/repos/asf/commons-rng/tree/2753012c Diff: http://git-wip-us.apache.org/repos/asf/commons-rng/diff/2753012c Branch: refs/heads/master Commit: 2753012cca4f998d6414e7f14e7448dd6bb2b465 Parents: e8f3134 Author: Gilles <er...@apache.org> Authored: Thu Nov 17 18:58:46 2016 +0100 Committer: Gilles <er...@apache.org> Committed: Thu Nov 17 18:58:46 2016 +0100 ---------------------------------------------------------------------- .../sampling/distribution/InternalGamma.java | 265 +------------------ 1 file changed, 9 insertions(+), 256 deletions(-) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/commons-rng/blob/2753012c/commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/InternalGamma.java ---------------------------------------------------------------------- diff --git a/commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/InternalGamma.java b/commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/InternalGamma.java index 2feb273..17ee050 100644 --- a/commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/InternalGamma.java +++ b/commons-rng-sampling/src/main/java/org/apache/commons/rng/sampling/distribution/InternalGamma.java @@ -49,7 +49,6 @@ package org.apache.commons.rng.sampling.distribution; * this library are license free. Since no such notice appears in the code these * functions can safely be ported to Commons-Math. * </p> - * */ class InternalGamma { // Class is package-private on purpose; do not make it public. /** @@ -79,119 +78,6 @@ class InternalGamma { // Class is package-private on purpose; do not make it pub /** Avoid repeated computation of log of 2 PI in logGamma */ private static final double HALF_LOG_2_PI = 0.5 * Math.log(2.0 * Math.PI); - /* - * Constants for the computation of double invGamma1pm1(double). - * Copied from DGAM1 in the NSWC library. - */ - - /** The constant {@code A0} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_A0 = .611609510448141581788E-08; - - /** The constant {@code A1} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_A1 = .624730830116465516210E-08; - - /** The constant {@code B1} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_B1 = .203610414066806987300E+00; - - /** The constant {@code B2} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_B2 = .266205348428949217746E-01; - - /** The constant {@code B3} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_B3 = .493944979382446875238E-03; - - /** The constant {@code B4} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_B4 = -.851419432440314906588E-05; - - /** The constant {@code B5} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_B5 = -.643045481779353022248E-05; - - /** The constant {@code B6} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_B6 = .992641840672773722196E-06; - - /** The constant {@code B7} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_B7 = -.607761895722825260739E-07; - - /** The constant {@code B8} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_B8 = .195755836614639731882E-09; - - /** The constant {@code P0} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_P0 = .6116095104481415817861E-08; - - /** The constant {@code P1} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_P1 = .6871674113067198736152E-08; - - /** The constant {@code P2} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_P2 = .6820161668496170657918E-09; - - /** The constant {@code P3} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_P3 = .4686843322948848031080E-10; - - /** The constant {@code P4} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_P4 = .1572833027710446286995E-11; - - /** The constant {@code P5} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_P5 = -.1249441572276366213222E-12; - - /** The constant {@code P6} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_P6 = .4343529937408594255178E-14; - - /** The constant {@code Q1} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_Q1 = .3056961078365221025009E+00; - - /** The constant {@code Q2} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_Q2 = .5464213086042296536016E-01; - - /** The constant {@code Q3} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_Q3 = .4956830093825887312020E-02; - - /** The constant {@code Q4} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_Q4 = .2692369466186361192876E-03; - - /** The constant {@code C} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C = -.422784335098467139393487909917598E+00; - - /** The constant {@code C0} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C0 = .577215664901532860606512090082402E+00; - - /** The constant {@code C1} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C1 = -.655878071520253881077019515145390E+00; - - /** The constant {@code C2} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C2 = -.420026350340952355290039348754298E-01; - - /** The constant {@code C3} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C3 = .166538611382291489501700795102105E+00; - - /** The constant {@code C4} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C4 = -.421977345555443367482083012891874E-01; - - /** The constant {@code C5} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C5 = -.962197152787697356211492167234820E-02; - - /** The constant {@code C6} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C6 = .721894324666309954239501034044657E-02; - - /** The constant {@code C7} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C7 = -.116516759185906511211397108401839E-02; - - /** The constant {@code C8} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C8 = -.215241674114950972815729963053648E-03; - - /** The constant {@code C9} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C9 = .128050282388116186153198626328164E-03; - - /** The constant {@code C10} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C10 = -.201348547807882386556893914210218E-04; - - /** The constant {@code C11} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C11 = -.125049348214267065734535947383309E-05; - - /** The constant {@code C12} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C12 = .113302723198169588237412962033074E-05; - - /** The constant {@code C13} defined in {@code DGAM1}. */ - private static final double INV_GAMMA1P_M1_C13 = -.205633841697760710345015413002057E-06; - /** * Class contains only static methods. */ @@ -220,29 +106,14 @@ class InternalGamma { // Class is package-private on purpose; do not make it pub * @return \( \ln \Gamma(x) \), or {@code NaN} if {@code x <= 0}. */ public static double logGamma(double x) { - double ret; - - if (Double.isNaN(x) || (x <= 0.0)) { - ret = Double.NaN; - } else if (x < 0.5) { - return logGamma1p(x) - Math.log(x); - } else if (x <= 2.5) { - return logGamma1p((x - 0.5) - 0.5); - } else if (x <= 8.0) { - final int n = (int) Math.floor(x - 1.5); - double prod = 1.0; - for (int i = 1; i <= n; i++) { - prod *= x - i; - } - return logGamma1p(x - (n + 1)) + Math.log(prod); - } else { - double sum = lanczos(x); - double tmp = x + LANCZOS_G + .5; - ret = ((x + .5) * Math.log(tmp)) - tmp + - HALF_LOG_2_PI + Math.log(sum / x); - } - - return ret; + // Stripped-down version of the same method defined in "Commons Math": + // Unused "if" branches (for when x < 8) have been removed here since + // this method is only used (by class "InternalUtils") in order to + // compute log(n!) for x > 20. + + final double sum = lanczos(x); + final double tmp = x + LANCZOS_G + 0.5; + return ((x + 0.5) * Math.log(tmp)) - tmp + HALF_LOG_2_PI + Math.log(sum / x); } /** @@ -266,129 +137,11 @@ class InternalGamma { // Class is package-private on purpose; do not make it pub * <a href="http://my.fit.edu/~gabdo/gamma.txt";>Note on the computation * of the convergent Lanczos complex Gamma approximation</a> */ - public static double lanczos(final double x) { + private static double lanczos(final double x) { double sum = 0.0; for (int i = LANCZOS.length - 1; i > 0; --i) { sum += LANCZOS[i] / (x + i); } return sum + LANCZOS[0]; } - - /** - * Computes the function \( \frac{1}{\Gamma(1 + x)} - 1 \) for \( -0.5 \leq x \leq 1.5 \). - * <p> - * This implementation is based on the double precision implementation in - * the <em>NSWC Library of Mathematics Subroutines</em>, {@code DGAM1}. - * </p> - * - * @param x Argument. - * @return \( \frac{1}{\Gamma(1 + x)} - 1 \) - * @throws IllegalArgumentException if {@code x < -0.5} - * @throws IllegalArgumentException if {@code x > 1.5} - */ - public static double invGamma1pm1(final double x) { - - if (x < -0.5) { - throw new IllegalArgumentException(); - } - if (x > 1.5) { - throw new IllegalArgumentException(); - } - - final double ret; - final double t = x <= 0.5 ? x : (x - 0.5) - 0.5; - if (t < 0.0) { - final double a = INV_GAMMA1P_M1_A0 + t * INV_GAMMA1P_M1_A1; - double b = INV_GAMMA1P_M1_B8; - b = INV_GAMMA1P_M1_B7 + t * b; - b = INV_GAMMA1P_M1_B6 + t * b; - b = INV_GAMMA1P_M1_B5 + t * b; - b = INV_GAMMA1P_M1_B4 + t * b; - b = INV_GAMMA1P_M1_B3 + t * b; - b = INV_GAMMA1P_M1_B2 + t * b; - b = INV_GAMMA1P_M1_B1 + t * b; - b = 1.0 + t * b; - - double c = INV_GAMMA1P_M1_C13 + t * (a / b); - c = INV_GAMMA1P_M1_C12 + t * c; - c = INV_GAMMA1P_M1_C11 + t * c; - c = INV_GAMMA1P_M1_C10 + t * c; - c = INV_GAMMA1P_M1_C9 + t * c; - c = INV_GAMMA1P_M1_C8 + t * c; - c = INV_GAMMA1P_M1_C7 + t * c; - c = INV_GAMMA1P_M1_C6 + t * c; - c = INV_GAMMA1P_M1_C5 + t * c; - c = INV_GAMMA1P_M1_C4 + t * c; - c = INV_GAMMA1P_M1_C3 + t * c; - c = INV_GAMMA1P_M1_C2 + t * c; - c = INV_GAMMA1P_M1_C1 + t * c; - c = INV_GAMMA1P_M1_C + t * c; - if (x > 0.5) { - ret = t * c / x; - } else { - ret = x * ((c + 0.5) + 0.5); - } - } else { - double p = INV_GAMMA1P_M1_P6; - p = INV_GAMMA1P_M1_P5 + t * p; - p = INV_GAMMA1P_M1_P4 + t * p; - p = INV_GAMMA1P_M1_P3 + t * p; - p = INV_GAMMA1P_M1_P2 + t * p; - p = INV_GAMMA1P_M1_P1 + t * p; - p = INV_GAMMA1P_M1_P0 + t * p; - - double q = INV_GAMMA1P_M1_Q4; - q = INV_GAMMA1P_M1_Q3 + t * q; - q = INV_GAMMA1P_M1_Q2 + t * q; - q = INV_GAMMA1P_M1_Q1 + t * q; - q = 1.0 + t * q; - - double c = INV_GAMMA1P_M1_C13 + (p / q) * t; - c = INV_GAMMA1P_M1_C12 + t * c; - c = INV_GAMMA1P_M1_C11 + t * c; - c = INV_GAMMA1P_M1_C10 + t * c; - c = INV_GAMMA1P_M1_C9 + t * c; - c = INV_GAMMA1P_M1_C8 + t * c; - c = INV_GAMMA1P_M1_C7 + t * c; - c = INV_GAMMA1P_M1_C6 + t * c; - c = INV_GAMMA1P_M1_C5 + t * c; - c = INV_GAMMA1P_M1_C4 + t * c; - c = INV_GAMMA1P_M1_C3 + t * c; - c = INV_GAMMA1P_M1_C2 + t * c; - c = INV_GAMMA1P_M1_C1 + t * c; - c = INV_GAMMA1P_M1_C0 + t * c; - - if (x > 0.5) { - ret = (t / x) * ((c - 0.5) - 0.5); - } else { - ret = x * c; - } - } - - return ret; - } - - /** - * Computes the function \( \ln \Gamma(1 + x) \) for \( -0.5 \leq x \leq 1.5 \). - * <p> - * This implementation is based on the double precision implementation in - * the <em>NSWC Library of Mathematics Subroutines</em>, {@code DGMLN1}. - * </p> - * - * @param x Argument. - * @return \( \ln \Gamma(1 + x) \) - * @throws IllegalArgumentException if {@code x < -0.5}. - * @throws IllegalArgumentException if {@code x > 1.5}. - */ - public static double logGamma1p(final double x) { - - if (x < -0.5) { - throw new IllegalArgumentException(); - } - if (x > 1.5) { - throw new IllegalArgumentException(); - } - - return -Math.log1p(invGamma1pm1(x)); - } }
