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DRANDMULTINORMAL / SRANDMULTINORMAL
Generates an array of random variates from a Multivariate Normal distribution with probability density function, f(X), where: f(X) = sqrt([det(C^(-1))] / [(2 * Pi)^M]) * exp(-(X - u)^T * C^(-1) * (X - u)), where u is the vector of means, XMU.
(Note that SRANDMULTINORMAL is the single precision version of DRANDMULTINORMAL. The argument lists of both routines are identical except that any double precision arguments of DRANDMULTINORMAL are replaced in SRANDMULTINORMAL by single precision arguments - type REAL in FORTRAN or type float in C).
— Input/Output: INTEGER STATE(*)
The STATE vector holds information on the state of the base generator being used and as such its minimum length varies. Prior to calling
DRANDMULTINORMAL
STATE must have been initialized. See Initialization of the Base Generators for information on initialization of the STATE variable.
On input: the current state of the base generator.
On output: the updated state of the base generator.
Example:
C Generate 100 values from the C Multivariate Normal distribution INTEGER LSTATE,N, MM PARAMETER (LSTATE=16,N=100,MM=10) INTEGER I,J,INFO,SEED(1),STATE(LSTATE) INTEGER LDC,LDX,M DOUBLE PRECISION X(N,MM),XMU(MM),C(MM,MM) C Set array sizes LDC = MM LDX = N C Set the seed SEED(1) = 1234 C Read in the distributional parameters READ(5,*) M READ(5,*) (XMU(I),I=1,M) DO 20 I = 1,M READ(5,*) (C(I,J),J=1,M) 20 CONTINUE C Initialize the STATE vector CALL DRANDINITIALIZE(1,1,SEED,1,STATE,LSTATE,INFO) C Generate N variates from the C Multivariate Normal distribution CALL DRANDMULTINORMAL(N,M,XMU,C,LDC,STATE,X,LDX,INFO) C Print the results DO 40 I = 1,N WRITE(6,*) (X(I,J),J=1,M) 40 CONTINUE |