Lapack error with SGETRF -

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i using lapack library solve optimization problem. getting different lapack errors (lapack error(1,2,3,4) sgetrf). there documentation source, can read understand these errors mean?

most of lapack routines return error code in argument info. meaning of output specified in documentation of function sgetrf()

if info null, everething ok ! if info <0 , error detected in input parameters. instance, sgetrf():

  • info=-1 : number of rows of matrix negative
  • info=-2 : number of columns of matrix negative
  • info=-4 : lda lower max( 1, m )

the routine xerbla() can applied print right error message:

xerbla( 'sgetrf', -info )

if info>0, document describes happening :

u(i,i) zero. factorization has been completed, factor u singular, , division 0 occur if used solve system of equations.

this problem can occur if matrix singular or ill-conditionned. if matrix a singular, there might different solutions, or no solution @ problem ax=b. if info=1, matrix null.

hence, testing info considered practice functions such sgetrf() or sgesv() called...


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