p?potrs

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

p?potrs

Solves a system of linear equations with a Cholesky-factored symmetric/Hermitian distributed positive-definite matrix.

Syntax

call pspotrs ( uplo , n , nrhs , a , ia , ja , desca , b , ib , jb , descb , info )

call pdpotrs ( uplo , n , nrhs , a , ia , ja , desca , b , ib , jb , descb , info )

call pcpotrs ( uplo , n , nrhs , a , ia , ja , desca , b , ib , jb , descb , info )

call pzpotrs ( uplo , n , nrhs , a , ia , ja , desca , b , ib , jb , descb , info )

Include Files

mkl_scalapack.h

Description

pspotrs pdpotrs pcpotrs pzpotrs The p?potrs routine function solves for X a system of distributed linear equations in the form:

sub( A )* X = sub( B ) ,

where sub( A ) = A ( ia : ia + n -1, ja : ja + n -1) is an n -by- n real symmetric or complex Hermitian positive definite distributed matrix, and sub( B ) denotes the distributed matrix B ( ib : ib + n -1, jb : jb + nrhs -1).

This routine function uses Cholesky factorization

sub( A ) = U^:code:`H`*U , or sub( A ) = L*L^:code:`H`

computed by p?potrf (Computes the Cholesky factorization of a symmetric (Hermitian) positive-definite distributed matrix.) .

Input Parameters

uplo

(global) CHARACTER*1 . Must be ‘U’ or ‘L’ .

If uplo = 'U' , upper triangle of sub( A ) is stored; If uplo = 'L' , lower triangle of sub( A ) is stored.

n

(global) INTEGER . The order of the distributed matrix sub( A ) (n≥0) .

nrhs

(global) INTEGER . The number of right hand sides; the number of columns of the distributed matrix sub( B ) (nrhs≥0) .

a , b

(local) REAL for pspotrs DOUBLE PRECISION for pdpotrs COMPLEX for pcpotrs DOUBLE COMPLEX for pzpotrs . Pointers into the local memory to arrays of local sizes

(lld_a,LOCc(ja+n-1)) and (lld_b,LOCc(jb+nrhs-1)) , respectively.

The array a contains the factors L or U from the Cholesky factorization sub( A ) = L * L^:code:`H` or sub( A ) = U^:code:`H`*U , as computed by p?potrf . On entry, the array b contains the local pieces of the right hand sides sub( B ).

ia , ja

(global) INTEGER . The row and column indices in the global matrix A indicating the first row and the first column of the matrix sub( A ), respectively.

desca

(global and local) INTEGER array of size dlen_ . The array descriptor for the distributed matrix A .

ib , jb

(global) INTEGER . The row and column indices in the global matrix B indicating the first row and the first column of the matrix sub( B ), respectively.

descb

(local) INTEGER array of size dlen_ . The array descriptor for the distributed matrix B .

Output Parameters

b: Overwritten by the local pieces of the solution matrix X .

info

INTEGER . If info=0 , the execution is successful.

info < 0 : if the i -th argument is an array and the j- th entry had an illegal value, then info = -( i *100+ j ); if the i- th argument is a scalar and had an illegal value, then info = -i .

NOTE:

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

p?potrs

Syntax

Include Files

Description

Input Parameters

Output Parameters