ALNPR

This function evaluates the lognormal probability density function.

Function Return Value

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

Required Arguments

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

AMU — Location parameter of the lognormal probability function. (Input)

SIGMA — Shape parameter of the lognormal probability function. SIGMA must be greater than 0. (Input)

FORTRAN 90 Interface

Generic: ALNPR (X, AMU, SIGMA)

Specific: The specific interface names are S_ALNPR and D_ALNPR.

FORTRAN 77 Interface

Single: ALNPR (X, AMU, SIGMA)

Double: The double precision name is DLNPR.

Description

The function ALNPR evaluates the lognormal probability density function, defined as

 

Example

In this example, we evaluate the probability function at X = 1.0, AMU = 0.0, SIGMA = 0.5.

 

USE UMACH_INT

USE ALNPR_INT

IMPLICIT NONE

INTEGER NOUT

REAL X, AMU, SIGMA, PR

CALL UMACH(2, NOUT)

X = 1.0

AMU = 0.0

SIGMA = 0.5

PR = ALNPR(X, AMU, SIGMA)

WRITE (NOUT, 99999) X, AMU, SIGMA, PR

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

END

Output

 

ALNPR( 1.00, 0.00, 0.50) = 0.7979