This function evaluates the Rayleigh probability density function.

Function Return Value

RALPR — Function value, the value of the probability density function.   (Output)

Required Arguments

X — Argument for which the Rayleigh probability density function is to be evaluated.   (Input)

ALPHA — Scale parameter of the Rayleigh probability function.   (Input)

FORTRAN 90 Interface

Generic:                              RALPR (X, ALPHA)

Specific:                             The specific interface names are S_RALPR and D_RALPR.

FORTRAN 77 Interface

Single:                                RALPR (X, ALPHA)

Double:                              The double precision name is DRALPR.

Description

The function RALPR evaluates the Rayleigh probability density function, which is a special case of the Weibull probability density function where GAMMA is equal to 2.0, and is defined as

Example

In this example, we evaluate the Rayleigh probability density function at X = 0.25,  ALPHA = 0.5.

 

      USE UMACH_INT
      USE RALPR_INT
      IMPLICIT NONE

      INTEGER NOUT

      REAL X, ALPHA, PR

      CALL UMACH(2, NOUT)

      X = 0.25

      ALPHA = 0.5

      PR = RALPR(X, ALPHA)

      WRITE (NOUT, 99999) X, ALPHA, PR

99999 FORMAT (' RALPR(', F4.2, ', ', F4.2, ') = ', F6.4)

      END

Output

 

RALPR(0.25, 0.50) = 0.8825

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