HP MLIB User's Guide Vol. 2 7th Ed.

602 HP MLIB User’s Guide

STCONV/DTCONV Tapered correlation and convolution

Output y The tapered convolution or correlation vector y of

length m. leny = (m−1)×|incy|+1.

Notes These subprograms do not use the BLAS indexing scheme described in “BLAS

Indexing Conventions” in the introduction to Chapter 2. Indexing works the

same way as the BLAS for a positive increment, but for a negative increment,

these subprograms access data backward from the beginning of the array

passed to it rather than from the end. To index backward through an array, as

desired for a convolution, the ending location of the array should be passed to

the subprogram. Refer to “Example 2” on page 602.

Example 1 Compute the discrete tapered correlation of the REAL*4 vectors x = (4, 1) and

w = (2, 1) stored in arrays X and W, respectively. In this instance, n = 2 and

m =4.

INTEGER*4 INCX,INCW,INCY,M,N

REAL*4 X(2),W(2),Y(4)

DATA X / 4.0 , 1.0 /

DATA W / 2.0 , 1.0 /

M = 4

N = 2

INCX = 1

INCW = 1

INCY = 1

CALL STCONV (X,INCX,W,INCW,Y,INCY,M,N)

The result is

Example 2 Compute the discrete tapered convolution of the REAL*4 vectors x = (1, 3) and

w = (2, 1) stored in arrays X and W, respectively.

INTEGER*4 INCX,INCW,INCY,M,N

REAL*4 X(2),W(2),Y(2)

DATA X / 1.0 , 3.0 /

DATA W / 2.0 , 1.0 /

M = 2

N = 2

INCX = 1

INCW = -1

INCY = 1

CALL STCONV (X,INCX,W(N),INCW,Y,INCY,M,N)

The result is

9200,,,().=

73,().=