Convolution or Correlation

Calling Sequence

CALL SCNVCOR	(CNVCOR, METHOD, NX, SX, IFX, INCX, NY, NPRE, M, SY, IFY, INC1Y, INC2Y, NZ, K, SZ, IFZ, INC1Z, INC2Z, SWORK, LWORK)
CALL DCNVCOR	(CNVCOR, METHOD, NX, DX, IFX, INCX, NY, NPRE, M, DY, IFY, INC1Y, INC2Y, NZ, K, DZ, IFZ, INC1Z, INC2Z, DWORK, LWORK)
CALL CCNVCOR	(CNVCOR, METHOD, NX, CX, IFX, INCX, NY, NPRE, M, CY, IFY, INC1Y, INC2Y, NZ, K, CZ, IFZ, INC1Z, INC2Z, CWORK, LWORK)
CALL ZCNVCOR	(CNVCOR, METHOD, NX, ZX, IFX, INCX, NY, NPRE, M, ZY, IFY, INC1Y, INC2Y, NZ, K, ZZ, IFZ, INC1Z, INC2Z, ZWORK, LWORK)
void scnvcor	(char cnvcor, char method, int nx, float *sx, int ifx, int incx, int ny, int npre, int m, float *sy, int ify, int inc1y, int inc2y, int nz, int k, float *sz, int ifz, int inc1z, int inc2z, float *swork, int lwork)
void dcnvcor	(char cnvcor, char method, int nx, double *dx, int ifx, int incx, int ny, int npre, int m, double *dy, int ify, int inc1y, int inc2y, int nz, int k, double *dz, int ifz, int inc1z, int inc2z, double *dwork, int lwork)
void ccnvcor	(char cnvcor, char method, int nx, complex *cx, int ifx, int incx, int ny, int npre, int m, complex *cy, int ify, int inc1y, int inc2y, int nz, int k, complex *cz, int ifz, int inc1z, int inc2z, complex *cwork, int lwork)
void zcnvcor	(char cnvcor, char method, int nx, doublecomplex *zx, int ifx, int incx, int ny, int npre, int m, doublecomplex *zy, int ify, int inc1y, int inc2y, int nz, int k, doublecomplex *zz, int ifz, int inc1z, int inc2z, doublecomplex *zwork, int lwork)

Arguments

CNVCOR	Indicates whether to perform convolution or correlation. The legal values for CNVCOR are listed below. Any values not listed below are illegal. `V' or `v' Convolution `R' or `r' Correlation
METHOD	Indicates which method to use to compute the convolution or correlation. The legal values for METHOD are listed below. Any values not listed below are illegal. `T' or `t' Fourier transform `D' or `d' Direct method
NX	On entry, the length of the X vector. NX 0.
xX	On entry, the filter vector xX(*).
IFX	On entry, the first element of xX to use. IFX > 0 for FORTRAN interfaces and IFX 0 for C interfaces.
INCX	On entry, the stride between elements of xX. INCX > 0.
NY	On entry, the length of the Y vector. NY 0.
NPRE	On entry, the number of implicit zeros prepended to each Y vector.
M	On entry, the number of Y vectors. M 0.
xY	On entry, the array of Y vectors Y(LDY,*).
IFY	On entry, the first element of xY to use. IFY > 0 for FORTRAN interfaces and IFY 0 for C interfaces.
INC1Y	On entry, the stride between elements of Y. INC1Y 0.
INC2Y	On entry, the stride between Y vectors. INC2Y 0.
NZ	On entry, the length of output vectors. NZ 0.
K	On entry, the number of output vectors. K 0.
xZ	Undefined on entry. On exit, the output vectors Z(LDZ,*).
IFZ	On entry, the first element of xZ to use. IFZ > 0 for FORTRAN interfaces and IFZ 0 for C interfaces.
INC1Z	On entry, the stride between elements of a Z vector. INC1Z 0.
INC2Z	On entry, the stride between Z vectors. INC2Z 0.
xWORK	On entry, an array with dimension of at least (NX + NY + NZ + 45). For the Fourier method, the first element of the work array should be zero the first time the routines are called. After the first call, as long as the work array has not been altered and the values of NX, NY, and NZ are the same, the same work array can be reused and the routine will be able to run faster. If the work array is changed or is used for different values of NX, NY, or NZ then set the first element of xWORK to zero before calling this routine.
xLWORK	On entry, the length of xWORK.

Sample Program

PROGRAM TEST

IMPLICIT NONE

C

INTEGER LWORK

INTEGER N

PARAMETER (N = 3)

PARAMETER (LWORK = 4 * N + 15)

C

COMPLEX P1(N), P2(N), P3(2*N-1), WORK(LWORK)

C

DATA P1 / 1, 2, 3 /, P2 / 4, 5, 6 /

C

EXTERNAL CCNVCOR

C

PRINT *, `P1:'

PRINT 1000, P1

PRINT *, `P2:'

PRINT 1000, P2

C

CALL CCNVCOR (`V', `T', N, P1, 1, 1, N, 0, 1, P2, 1, 1, 1,

$ 2 * N - 1, 1, P3, 1, 1, 1, WORK, LWORK)

C

PRINT *, `P3:'

PRINT 1000, P3

C

1000 FORMAT (1X, 100(F4.1' +',F4.1,'i `))

C

END

Sample Output

P1:

1.0 + 0.0i 2.0 + 0.0i 3.0 + 0.0i

P2:

4.0 + 0.0i 5.0 + 0.0i 6.0 + 0.0i

P3:

4.0 + 0.0i 13.0 + 0.0i 28.0 + 0.0i 27.0 + 0.0i 18.0 + 0.0i