MathFunctions

java.lang.Object
- jdistlib.math.MathFunctions

public class MathFunctions
extends java.lang.Object

Constructor Summary

Constructors
Constructor and Description

MathFunctions()

Constructors
Constructor and Description
`MathFunctions()`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static double`	`_expm1(double x)` Alternative expm1 -- no difference from Java's
`static double`	`_log1p(double x)` Alternative log1p.
`static double`	`algdiv(double a, double b)` ----------------------------------------------------------------------- COMPUTATION OF LN(GAMMA(B)/GAMMA(A+B)) WHEN B >= 8.
`static double`	`alnrel(double a)` ----------------------------------------------------------------------- Evaluation of the function ln(1 + a) -----------------------------------------------------------------------
`static double`	`apser(double a, double b, double x, double eps)`
`static double`	`basym(double a, double b, double lambda, double eps, boolean log_p)`
`static double`	`bcorr(double a0, double b0)` ----------------------------------------------------------------------- EVALUATION OF DEL(A0) + DEL(B0) - DEL(A0 + B0) WHERE LN(GAMMA(A)) = (A - 0.5)LN(A) - A + 0.5LN(2*PI) + DEL(A).
`static double`	`bd0(double x, double np)`
`static double`	`beta(double a, double b)` This function returns the value of the beta function evaluated with arguments a and b.
`static double`	`betaln(double a0, double b0)` ----------------------------------------------------------------------- Evaluation of the logarithm of the beta function ln(beta(a0,b0)) -----------------------------------------------------------------------
`static double`	`bfrac(double a, double b, double x, double y, double lambda, double eps, boolean log_p)`
`static double`	`bgrat(double a, double b, double x, double y, double w, double eps, int[] ierr, boolean log_w)`
`static double`	`bpser(double a, double b, double x, double eps, boolean log_p)`
`static double[]`	`bratio(double a, double b, double x, double y, boolean log_p)` ----------------------------------------------------------------------- Evaluation of the Incomplete Beta function I_x(a,b) -------------------- It is assumed that a and b are nonnegative, and that x <= 1 and y = 1 - x.
`static double`	`brcmp1(int mu, double a, double b, double x, double y, boolean give_log)`
`static double`	`brcomp(double a, double b, double x, double y, boolean log_p)`
`static double`	`bup(double a, double b, double x, double y, int n, double eps, boolean give_log)`
`static double`	`chebyshev_eval(double x, double[] a, int n)` evaluate the n-term Chebyshev series "a" at "x".
`static double`	`choose(double n, double k)`
`static double`	`cospi(double x)`
`static double`	`erf__(double x)` ----------------------------------------------------------------------- EVALUATION OF THE REAL ERROR FUNCTION -----------------------------------------------------------------------
`static double`	`erfc1(int ind, double x)` ----------------------------------------------------------------------- EVALUATION OF THE COMPLEMENTARY ERROR FUNCTION ERFC1(IND,X) = ERFC(X) IF IND = 0 ERFC1(IND,X) = EXP(XX)ERFC(X) OTHERWISE -----------------------------------------------------------------------
`static double`	`esum(int mu, double x, boolean give_log)` ----------------------------------------------------------------------- EVALUATION OF EXP(MU + X) -----------------------------------------------------------------------
`static double`	`exparg(int l)` --------------------------------------------------------------------
`static double`	`fpser(double a, double b, double x, double eps, boolean log_p)`
`static double`	`frexp(double x, int[] i)` Implementation of frexp
`static double`	`gam1(double a)` ------------------------------------------------------------------ COMPUTATION OF 1/GAMMA(A+1) - 1 FOR -0.5 <= A <= 1.5 ------------------------------------------------------------------
`static double`	`gamln(double a)` ----------------------------------------------------------------------- Evaluation of ln(gamma(a)) for positive a ----------------------------------------------------------------------- Written by Alfred H.
`static double`	`gamln1(double a)` ----------------------------------------------------------------------- EVALUATION OF LN(GAMMA(1 + A)) FOR -0.2 <= A <= 1.25 -----------------------------------------------------------------------
`static double`	`gamma_cody(double x)` ---------------------------------------------------------------------- This routine calculates the GAMMA function for a float argument X.
`static double`	`gammafn(double x)`
`static double[]`	`gammafn(double[] x)` Batch call gamma function
`static int`	`gcd(int m, int n)` Find greatest common divisor of m and n
`static double`	`gharmonic(int n)` Calculate harmonic number
`static double`	`gharmonic(int n, double s)`
`static double`	`gharmonic(int n, double s, double logexponent)` Calculate generalized harmonic number
`static double`	`grat_r(double a, double x, double log_r, double eps)`
`static double`	`gsumln(double a, double b)` ----------------------------------------------------------------------- EVALUATION OF THE FUNCTION LN(GAMMA(A + B)) FOR 1 <= A <= 2 AND 1 <= B <= 2 -----------------------------------------------------------------------
`static boolean`	`isFinite(double x)`
`static boolean`	`isInfinite(double x)`
`static boolean`	`isNonInt(double x)`
`static double`	`lbeta(double a, double b)`
`static double`	`lchoose(double n, double k)`
`static double`	`ldexp(double x, double ex)`
`static double`	`ldexp(double x, int p)` Implementation of ldexp
`static double`	`lgamma1p(double a)`
`static double`	`lgammacor(double x)`
`static double`	`lgammafn_sign(double x, int[] sgn)`
`static double`	`lgammafn(double x)`
`static double[]`	`lgammafn(double[] x)` Batch call log gamma function
`static double`	`lgharmonic(int n)`
`static double`	`lgharmonic(int n, double s)`
`static double`	`lgharmonic(int n, double s, double logexponent)` Calculate the log of generalized harmonic number
`static double`	`lmvgammafn(double a, int p)` Log of multivariate gamma function By: Roby Joehanes
`static double`	`log1pmx(double x)`
`static double`	`log1px(double x)` log1px takes a double and returns a double.
`static double`	`logspace_add(double logx, double logy)` Compute the log of a sum from logs of terms, i.e., log (exp (logx) + exp (logy)) without causing overflows and without throwing away large handfuls of accuracy.
`static double`	`logspace_sub(double logx, double logy)` Compute the log of a difference from logs of terms, i.e., log (exp (logx) - exp (logy)) without causing overflows and without throwing away large handfuls of accuracy.
`static double`	`logspace_sum(double[] logx)`
`static double`	`pd_lower_cf(double y, double d)`
`static double`	`pd_lower_series(double lambda, double y)`
`static double`	`pd_upper_series(double x, double y, boolean log_p)`
`static double`	`psi(double x)` --------------------------------------------------------------------- Evaluation of the Digamma function psi(x) ----------- Psi(xx) is assigned the value 0 when the digamma function cannot be computed.
`static double`	`rexpm1(double x)` ----------------------------------------------------------------------- EVALUATION OF THE FUNCTION EXP(X) - 1 -----------------------------------------------------------------------
`static double`	`rlog1(double x)` ----------------------------------------------------------------------- Evaluation of the function x - ln(1 + x) -----------------------------------------------------------------------
`static double`	`round(double val, int places)` Rounding to desired num places
`static float`	`round(float val, int places)`
`static double`	`signif(double val, int places)` Mimicking R's signif
`static double`	`sinc(double x)` Compute sinc(x) = sin(x)/x for x != 0.
`static double`	`sinpi(double x)`
`static double`	`stirlerr(double n)`
`static double`	`tanpi(double x)`
`static double`	`trunc(double x)`

Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail
- MathFunctions
```
public MathFunctions()
```

Method Detail

lmvgammafn
```
public static final double lmvgammafn(double a,
                                      int p)
```
Log of multivariate gamma function By: Roby Joehanes

Parameters:

a -

p - the order (or dimension)

Returns:

log multivariate gamma

trunc

public static final double trunc(double x)

round

public static final double round(double val,
                                 int places)

Rounding to desired num places

Parameters:: val -; places -
Returns:: rounded number

round

public static final float round(float val,
                                int places)

signif

public static final double signif(double val,
                                  int places)

Mimicking R's signif

Parameters:: val -; places -
Returns:: rounded values

gcd
```
public static final int gcd(int m,
                            int n)
```
Find greatest common divisor of m and n

Parameters:

m -

n -

Returns:

GCD(m, n)

sinc
```
public static final double sinc(double x)
```
Compute sinc(x) = sin(x)/x for x != 0. Return 1 when x == 0.

Parameters:

x -

Returns:

sinc value

isFinite

public static final boolean isFinite(double x)

isInfinite

public static final boolean isInfinite(double x)

ldexp

public static final double ldexp(double x,
                                 double ex)

chebyshev_eval

public static final double chebyshev_eval(double x,
                                          double[] a,
                                          int n)

evaluate the n-term Chebyshev series "a" at "x".

Parameters:: x -; a -; n -
Returns:: Chebyshev function result

lgammacor

public static final double lgammacor(double x)

lgammafn_sign

public static final double lgammafn_sign(double x,
                                         int[] sgn)

lgammafn

public static final double lgammafn(double x)

lgammafn
```
public static final double[] lgammafn(double[] x)
```
Batch call log gamma function

Parameters:

x -

Returns:

an array of results

stirlerr

public static final double stirlerr(double n)

gammafn

public static final double gammafn(double x)

gammafn
```
public static final double[] gammafn(double[] x)
```
Batch call gamma function

Parameters:

x -

Returns:

an array of results

bd0

public static final double bd0(double x,
                               double np)

lbeta

public static final double lbeta(double a,
                                 double b)

log1pmx

public static final double log1pmx(double x)

log1px
```
public static final double log1px(double x)
```
log1px takes a double and returns a double. It is a Taylor series expansion of log(1+x). x is presumed to be < 1. As I have called it, x < .1, and so I know the algorithm will terminate quickly. The closer x is to 1, the slower this will be. (From AS 885)

lgamma1p

public static final double lgamma1p(double a)

logspace_add
```
public static final double logspace_add(double logx,
                                        double logy)
```
Compute the log of a sum from logs of terms, i.e., log (exp (logx) + exp (logy)) without causing overflows and without throwing away large handfuls of accuracy.

logspace_sub
```
public static final double logspace_sub(double logx,
                                        double logy)
```
Compute the log of a difference from logs of terms, i.e., log (exp (logx) - exp (logy)) without causing overflows and without throwing away large handfuls of accuracy.

logspace_sum

public static final double logspace_sum(double[] logx)

bratio

public static final double[] bratio(double a,
                                    double b,
                                    double x,
                                    double y,
                                    boolean log_p)

-----------------------------------------------------------------------
              Evaluation of the Incomplete Beta function I_x(a,b)
                       --------------------
     It is assumed that a and b are nonnegative, and that x <= 1
     and y = 1 - x.  Bratio assigns w and w1 the values
                        w  = I_x(a,b)
                        w1 = 1 - I_x(a,b)
     ierr is a variable that reports the status of the results.
     If no input errors are detected then ierr is set to 0 and
     w and w1 are computed. otherwise, if an error is detected,
     then w and w1 are assigned the value 0 and ierr is set to
     one of the following values ...
          ierr = 1  if a or b is negative
          ierr = 2  if a = b = 0
          ierr = 3  if x < 0 or x > 1
          ierr = 4  if y < 0 or y > 1
          ierr = 5  if x + y != 1
          ierr = 6  if x = a = 0
          ierr = 7  if y = b = 0
          ierr = 8      (not used currently)
          ierr = 9  NaN in a, b, x, or y
          ierr = 10     (not used currently)
          ierr = 11  bgrat() error code 1 [+ warning in bgrat()]
          ierr = 12  bgrat() error code 2   (no warning here)
          ierr = 13  bgrat() error code 3   (no warning here)
          ierr = 14  bgrat() error code 4 [+ WARNING in bgrat()]
 --------------------
     Written by Alfred H. Morris, Jr.
          Naval Surface Warfare Center
          Dahlgren, Virginia
     Revised ... Nov 1991
 -----------------------------------------------------------------------

fpser

public static final double fpser(double a,
                                 double b,
                                 double x,
                                 double eps,
                                 boolean log_p)

apser

public static final double apser(double a,
                                 double b,
                                 double x,
                                 double eps)

bpser

public static final double bpser(double a,
                                 double b,
                                 double x,
                                 double eps,
                                 boolean log_p)

bup

public static final double bup(double a,
                               double b,
                               double x,
                               double y,
                               int n,
                               double eps,
                               boolean give_log)

bfrac

public static final double bfrac(double a,
                                 double b,
                                 double x,
                                 double y,
                                 double lambda,
                                 double eps,
                                 boolean log_p)

brcomp

public static final double brcomp(double a,
                                  double b,
                                  double x,
                                  double y,
                                  boolean log_p)

brcmp1

public static final double brcmp1(int mu,
                                  double a,
                                  double b,
                                  double x,
                                  double y,
                                  boolean give_log)

bgrat

public static final double bgrat(double a,
                                 double b,
                                 double x,
                                 double y,
                                 double w,
                                 double eps,
                                 int[] ierr,
                                 boolean log_w)

grat_r

public static final double grat_r(double a,
                                  double x,
                                  double log_r,
                                  double eps)

basym

public static final double basym(double a,
                                 double b,
                                 double lambda,
                                 double eps,
                                 boolean log_p)

exparg

public static final double exparg(int l)

--------------------------------------------------------------------

     IF L = 0 THEN  EXPARG(L) = THE LARGEST POSITIVE W FOR WHICH
     EXP(W) CAN BE COMPUTED.
     IF L IS NONZERO THEN  EXPARG(L) = THE LARGEST NEGATIVE W FOR
     WHICH THE COMPUTED VALUE OF EXP(W) IS NONZERO.
     NOTE... ONLY AN APPROXIMATE VALUE FOR EXPARG(L) IS NEEDED.

--------------------------------------------------------------------

esum
```
public static final double esum(int mu,
                                double x,
                                boolean give_log)
```
----------------------------------------------------------------------- EVALUATION OF EXP(MU + X) -----------------------------------------------------------------------

rexpm1
```
public static final double rexpm1(double x)
```
----------------------------------------------------------------------- EVALUATION OF THE FUNCTION EXP(X) - 1 -----------------------------------------------------------------------

alnrel
```
public static final double alnrel(double a)
```
----------------------------------------------------------------------- Evaluation of the function ln(1 + a) -----------------------------------------------------------------------

rlog1
```
public static final double rlog1(double x)
```
----------------------------------------------------------------------- Evaluation of the function x - ln(1 + x) -----------------------------------------------------------------------

erf__
```
public static final double erf__(double x)
```
----------------------------------------------------------------------- EVALUATION OF THE REAL ERROR FUNCTION -----------------------------------------------------------------------

erfc1
```
public static final double erfc1(int ind,
                                 double x)
```
----------------------------------------------------------------------- EVALUATION OF THE COMPLEMENTARY ERROR FUNCTION ERFC1(IND,X) = ERFC(X) IF IND = 0 ERFC1(IND,X) = EXP(X*X)*ERFC(X) OTHERWISE -----------------------------------------------------------------------

gam1
```
public static final double gam1(double a)
```
------------------------------------------------------------------ COMPUTATION OF 1/GAMMA(A+1) - 1 FOR -0.5 <= A <= 1.5 ------------------------------------------------------------------

gamln1
```
public static final double gamln1(double a)
```
----------------------------------------------------------------------- EVALUATION OF LN(GAMMA(1 + A)) FOR -0.2 <= A <= 1.25 -----------------------------------------------------------------------

psi

public static final double psi(double x)

 ---------------------------------------------------------------------
                 Evaluation of the Digamma function psi(x)
                           -----------
     Psi(xx) is assigned the value 0 when the digamma function cannot
     be computed.
     The main computation involves evaluation of rational Chebyshev
     approximations published in Math. Comp. 27, 123-127(1973) by
     Cody, Strecok and Thacher.
 ---------------------------------------------------------------------
     Psi was written at Argonne National Laboratory for the FUNPACK
     package of special function subroutines. Psi was modified by
     A.H. Morris (NSWC).
 ---------------------------------------------------------------------

betaln
```
public static final double betaln(double a0,
                                  double b0)
```
----------------------------------------------------------------------- Evaluation of the logarithm of the beta function ln(beta(a0,b0)) -----------------------------------------------------------------------

gsumln
```
public static final double gsumln(double a,
                                  double b)
```
----------------------------------------------------------------------- EVALUATION OF THE FUNCTION LN(GAMMA(A + B)) FOR 1 <= A <= 2 AND 1 <= B <= 2 -----------------------------------------------------------------------

bcorr
```
public static final double bcorr(double a0,
                                 double b0)
```
----------------------------------------------------------------------- EVALUATION OF DEL(A0) + DEL(B0) - DEL(A0 + B0) WHERE LN(GAMMA(A)) = (A - 0.5)*LN(A) - A + 0.5*LN(2*PI) + DEL(A). IT IS ASSUMED THAT A0 >= 8 AND B0 >= 8. -----------------------------------------------------------------------

algdiv
```
public static final double algdiv(double a,
                                  double b)
```
----------------------------------------------------------------------- COMPUTATION OF LN(GAMMA(B)/GAMMA(A+B)) WHEN B >= 8. IN THIS ALGORITHM, DEL(X) IS THE FUNCTION DEFINED BY LN(GAMMA(X)) = (X - 0.5)*LN(X) - X + 0.5*LN(2*PI) + DEL(X). -----------------------------------------------------------------------

gamln

public static final double gamln(double a)

 -----------------------------------------------------------------------
            Evaluation of  ln(gamma(a))  for positive a
 -----------------------------------------------------------------------
     Written by Alfred H. Morris
          Naval Surface Warfare Center
          Dahlgren, Virginia
 -----------------------------------------------------------------------

beta

public static final double beta(double a,
                                double b)

    This function returns the value of the beta function
    evaluated with arguments a and b.

  NOTES
    This routine is a translation into C of a Fortran subroutine
    by W. Fullerton of Los Alamos Scientific Laboratory.
    Some modifications have been made so that the routines
    conform to the IEEE 754 standard.

lchoose

public static final double lchoose(double n,
                                   double k)

choose

public static final double choose(double n,
                                  double k)

gamma_cody

public static final double gamma_cody(double x)

 ----------------------------------------------------------------------

           This routine calculates the GAMMA function for a float argument X.
           Computation is based on an algorithm outlined in reference [1].
           The program uses rational functions that approximate the GAMMA
           function to at least 20 significant decimal digits.  Coefficients
           for the approximation over the interval (1,2) are unpublished.
           Those for the approximation for X >= 12 are from reference [2].
           The accuracy achieved depends on the arithmetic system, the
           compiler, the intrinsic functions, and proper selection of the
           machine-dependent constants.



           Error returns

           The program returns the value XINF for singularities or
           when overflow would occur.    The computation is believed
           to be free of underflow and overflow.

           Intrinsic functions required are:

           INT, DBLE, EXP, LOG, REAL, SIN

           References:
           [1]  "An Overview of Software Development for Special Functions",
                W. J. Cody, Lecture Notes in Mathematics, 506,
                Numerical Analysis Dundee, 1975, G. A. Watson (ed.),
                Springer Verlag, Berlin, 1976.

           [2]  Computer Approximations, Hart, Et. Al., Wiley and sons, New York, 1968.

           Latest modification: October 12, 1989

           Authors: W. J. Cody and L. Stoltz
           Applied Mathematics Division
           Argonne National Laboratory
           Argonne, IL 60439
           ----------------------------------------------------------------------

pd_upper_series

public static final double pd_upper_series(double x,
                                           double y,
                                           boolean log_p)

pd_lower_cf

public static final double pd_lower_cf(double y,
                                       double d)

pd_lower_series

public static final double pd_lower_series(double lambda,
                                           double y)

_expm1
```
public static final double _expm1(double x)
```
Alternative expm1 -- no difference from Java's

Parameters:

x -

Returns:

expm1

_log1p
```
public static final double _log1p(double x)
```
Alternative log1p. No difference from Java's.

Parameters:

x -

Returns:

log1p

gharmonic
```
public static final double gharmonic(int n)
```
Calculate harmonic number

Parameters:

n - must be positive

Returns:

value

gharmonic

public static final double gharmonic(int n,
                                     double s)

gharmonic

public static final double gharmonic(int n,
                                     double s,
                                     double logexponent)

Calculate generalized harmonic number

Parameters:: n - must be positive; s -; logexponent -
Returns:: a value

lgharmonic

public static final double lgharmonic(int n)

lgharmonic

public static final double lgharmonic(int n,
                                      double s)

lgharmonic

public static final double lgharmonic(int n,
                                      double s,
                                      double logexponent)

Calculate the log of generalized harmonic number

Parameters:: n - must be positive; s -; logexponent -
Returns:: a value

cospi

public static final double cospi(double x)

sinpi

public static final double sinpi(double x)

tanpi

public static final double tanpi(double x)

frexp

public static final double frexp(double x,
                                 int[] i)

Implementation of frexp

Parameters:: x -; i - an array of 1 element
Returns:: frexp

ldexp

public static final double ldexp(double x,
                                 int p)

Implementation of ldexp

Parameters:: x -; p -
Returns:: ldexp

isNonInt

public static final boolean isNonInt(double x)

Class MathFunctions

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

MathFunctions

Method Detail

lmvgammafn

trunc

round

round

signif

gcd

sinc

isFinite

isInfinite

ldexp

chebyshev_eval

lgammacor

lgammafn_sign

lgammafn

lgammafn

stirlerr

gammafn

gammafn

bd0

lbeta

log1pmx

log1px

lgamma1p

logspace_add

logspace_sub

logspace_sum

bratio

fpser

apser

bpser

bup

bfrac

brcomp

brcmp1

bgrat

grat_r

basym

exparg

esum

rexpm1

alnrel

rlog1

erf__

erfc1

gam1

gamln1

psi

betaln

gsumln

bcorr

algdiv

gamln

beta

lchoose

choose

gamma_cody

pd_upper_series

pd_lower_cf

pd_lower_series

_expm1

_log1p

gharmonic

gharmonic

gharmonic

lgharmonic

lgharmonic

lgharmonic

cospi

sinpi

tanpi

frexp

ldexp

isNonInt