Developer Reference for Intel® oneAPI Math Kernel Library for C
?sfrk
Performs a symmetric rank-k operation for matrix in RFP format.
Syntax
lapack_intLAPACKE_ssfrk ( intmatrix_layout , chartransr , charuplo , chartrans , lapack_intn , lapack_intk , floatalpha , constfloat*a , lapack_intlda , floatbeta , float*c );
lapack_intLAPACKE_dsfrk ( intmatrix_layout , chartransr , charuplo , chartrans , lapack_intn , lapack_intk , doublealpha , constdouble*a , lapack_intlda , doublebeta , double*c );
Include Files
mkl.h
Description
ssfrk dsfrk sfrk
The ?sfrk routines perform a matrix-matrix operation using symmetric matrices. The operation is defined as
C := alpha * A * A:code:`T` + beta * C ,
or
C := alpha * A:code:`T` * A + beta * C ,
where:
alpha and beta are scalars,
C is an n -by- n symmetric matrix in rectangular full packed (RFP) format ,
A is an n -by- k matrix in the first case and a k -by- n matrix in the second case.
Input Parameters
- matrix_layout
-
Specifies whether matrix storage layout is row major ( LAPACK_ROW_MAJOR ) or column major ( LAPACK_COL_MAJOR ).
transr
if transr = 'N' or 'n' , the normal form of RFP C is stored; if transr= 'T' or 't' , the transpose form of RFP C is stored.
uplo
Specifies whether the upper or lower triangular part of the array c is used.
If uplo = 'U' or ‘u’ , then the upper triangular part of the array c is used. If uplo = 'L' or ‘l’ , then the low triangular part of the array c is used.
trans
Specifies the operation:
if trans = 'N' or 'n' , then C := alpha*A*A^{T} + beta*C ; if trans = 'T' or 't' , then C := alpha*A^{T}*A + beta*C ;
n
Specifies the order of the matrix C . The value of n must be at least zero.
k
On entry with trans = 'N' or ‘n’ , k specifies the number of columns of the matrix A , and on entry with trans = 'T' or ‘t’ , k specifies the number of rows of the matrix A .
The value of k must be at least zero.
- alpha
-
REAL for ssfrk DOUBLE PRECISION for dsfrk Specifies the scalar alpha .
- a
-
REAL for ssfrk DOUBLE PRECISION for dsfrk Array, DIMENSION (lda,ka) , where ka is k when trans = 'N' or ‘n’ , and is n otherwise. Before entry with trans = 'N' or ‘n’ , the leading n -by- k part of the array a must contain the matrix A , otherwise the leading k -by- n part of the array a must contain the matrix A .
- a
-
Array, size max(1,lda*ka) , where ka is in the following table: Col_major Row_major trans = ‘N’ kntrans = ‘T’ nk Before entry with trans = 'N' or ‘n’ , the leading n -by- k part of the array a must contain the matrix A , otherwise the leading k -by- n part of the array a must contain the matrix A .
- lda
-
INTEGER . Specifies the leading dimension of a as declared in the calling (sub)program. When trans = 'N' or ‘n’ , then lda must be at least max(1,n) , otherwise lda must be at least max(1, k) .
- lda
-
Specifies the leading dimension of a as declared in the calling (sub)program. lda is defined by the following table: Col_major Row_major trans = ‘N’ max(1,n)max(1,k)trans = ‘T’ max(1,k)max(1,n)
- beta
-
REAL for ssfrk DOUBLE PRECISION for dsfrk Specifies the scalar beta .
- c
-
REAL for ssfrk DOUBLE PRECISION for dsfrk Array, size (n*(n+1)/2 ) . Before entry contains the symmetric matrix C in RFP format .
Output Parameters
- c
-
If trans = 'N' or 'n' , then c contains C := alpha * A * A ‘ + beta * C ; if trans = 'T' or 't' , then c contains C := alpha*A'*A + beta*C ;
Return Values
This function returns a value info .
If info = 0 , the execution is successful.
If info < 0 , the i -th parameter had an illegal value.
If info = -1011 , memory allocation error occurred.