## Sparse RHS not yet supported

Open discussion for MAGMA library (Matrix Algebra on GPU and Multicore Architectures)
Ólafur
Posts: 9
Joined: Tue Jul 25, 2017 9:34 am

### Sparse RHS not yet supported

Hey

I've been working on spectral analysis problem with a huge Hermitian matrix. But when I call the magma_z_solver I get an error saying that sparse RHS is not yet supported. If I try making it dense it returns an error saying it's expecting a magma_z_matrix format RHS. I thought that magma_z_matrix was a sparse format?
At any rate, I'm not too interested in a vector on the right hand side since I only want the spectrum of the matrix. Unless the routine needs it for the actual calculation it would be nice to save myself the memory of storing a relatively large complex matrix since memory is my main limitation.

Code: Select all

``````//Compiles with the corresponding makefile.
//Takes in the 3 vectors of CSR format, creates MAGMA format sparse matrix, returns its spectrum.

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <math.h>

#include "magma_v2.h"
#include "magmasparse.h"

int main()
{
//Setup
int n = 3;  //Dimension of the nxn matrix

//Testing with matrix {{4,1-i,2+i},{1+i,-1,1},{2-i,1,3}} that has spectrum {6.08807,-1.61431,1.52624}

int *col; //Column indices of NNZ in A
col = (int*) calloc(n*n,   sizeof(int));
col = 0; col=1; col = 2;
col = 0; col=1; col = 2;
col = 0; col=1; col = 2;

int *row; //Row pointer of NNZ in A
row = (int*) calloc(n+1, sizeof(int));[code]//Compiles with the corresponding makefile.
row = 0;	row = 3;	row = 6;	row = 9;

//NNZ of the matrix A:
val = malloc(n*n*sizeof(magmaDoubleComplex)); //Allocates the struct on the stack
if (val == NULL)
{
fprintf( stderr, "malloc failed\n" );
return 0;
}
else
{
fprintf( stderr, "malloc succeeded\n" );
}

val = MAGMA_Z_MAKE(12,0);	val = MAGMA_Z_MAKE(1,-1);	val = MAGMA_Z_MAKE(2,1);
val = MAGMA_Z_MAKE(1,1);		val = MAGMA_Z_MAKE(-1,0);	val = MAGMA_Z_MAKE(1,0);
val = MAGMA_Z_MAKE(2,-1);	val = MAGMA_Z_MAKE(1,0);		val = MAGMA_Z_MAKE(3,0);

printf("val created successfully\n");

//Initialize MAGMA
magma_init();
magma_zopts opts;
magma_queue_t queue;
magma_queue_create(0, &queue);

magma_z_matrix A={Magma_CSR}, dA={Magma_CSR};
magma_z_matrix b={Magma_CSR}, db={Magma_CSR};
magma_z_matrix x={Magma_CSR}, dx={Magma_CSR};

//Pass the system to MAGMA
magma_zcsrset(n,n,row,col,val,&A,queue);

// Choose a solver, preconditioner, etc. - see documentation for options.
opts.solver_par.solver = Magma_LOBPCG; // choose an LOBPCG solver
opts.solver_par.num_eigenvalues = 3; // number of eigenvalues you want to compute
opts.solver_par.maxiter = 1000; // max number of iterations
opts.solver_par.rtol = 1e-10; // stopping criterion - relative accuracy of first eigenvalue
opts.precond_par.solver = Magma_ILU; // preconditioner
opts.precond_par.levels = 0; // ILU(0) - no fill-in
opts.precond_par.trisolver = Magma_CUSOLVE; //exact triangular solves

//Copy the system to device
magma_zmtransfer(A, &dA, Magma_CPU, Magma_DEV, queue);

//Generate the preconditioner
magma_z_precondsetup(dA, db, &opts.solver_par, &opts.precond_par, queue);

//Calling zlobpcg to find eigenvalues
magma_z_solver(dA, db, &dx, &opts, queue);
// magma_zlobpcg(A, &opts, &opts, queue);

//Then copy the solution back to the host
magma_zmfree( &x, queue );
magma_zmtransfer( dx, &x, Magma_CPU, Magma_DEV, queue );

//and back to the application code
magma_zvget( x, &n, &n, &sol, queue );

//Free the allocated memory...
magma_zmfree( &dx, queue );
magma_zmfree( &db, queue );
magma_zmfree( &dA, queue );

//and finalize MAGMA.
magma_queue_destroy( queue );
magma_finalize();

//Output
int i;
for (i = 0; i < n; ++i) {
printf("%.4f\n", sol[i]);
}[code]//Compiles with the corresponding makefile.
printf("\n\n\n\n");

return 0;
}``````
Many thanks, Ólafur