example.c

/*
This is a small example program which illustrates interfacing with the Mondriaan library.

It can be compiled using:

gcc example.c -I../src/include -L../src/lib -lMondriaan4 -lm

*/

#include <stdlib.h>
#include <stdio.h>
/* Make sure to include the Mondriaan headers. */
#include <Mondriaan.h>

int main(int argc, char **argv)
{
	/* This will contain the Mondriaan options. */
	struct opts Options;
	/* This file pointer will be the opened Matrix Market file. */
	FILE *File;
	/* This structure will contain the arc130 matrix. */
	struct sparsematrix Arc130;
	/* Variables used for calculating the communication volume. */
	long ComVolumeRow, ComVolumeCol, Dummy;
	/* Variables used to calculate the imbalance. */
	long MaxNrNz;
	double Imbalance;
	
	/* Set the default options. */
	SetDefaultOptions(&Options);
	
	/* We can also read options from disk. */
	/* if (!SetOptionsFromFile(&Options, "options.txt")) printf("Unable to set options from disk!\n"); */
	
	/* If we are done setting the options, we check and apply them. */
	if (!ApplyOptions(&Options))
	{
		printf("Invalid options!\n");
		return EXIT_FAILURE;
	}
	
	/* Open the arc130 matrix file. */
	if (!(File = fopen("../tests/arc130.mtx", "r")))
	{
		printf("Unable to open arc130!\n");
		return EXIT_FAILURE;
	}
	
	/* Read it from the file. */
	if (!MMReadSparseMatrix(File, &Arc130))
	{
		printf("Unable to read arc130!\n");
		fclose(File);
		return EXIT_FAILURE;
	}
	
	fclose(File);
	
	/* Distribute the matrix over two processors with an allowed imbalance of 3% and the options provided above. */
	if (!DistributeMatrixMondriaan(&Arc130, 2, 0.03, &Options, NULL))
	{
		printf("Unable to distribute arc130!\n");
		return EXIT_FAILURE;
	}
	
	/* Calculate the communication volume. */
	CalcCom(&Arc130, NULL, ROW, &ComVolumeRow, &Dummy, &Dummy, &Dummy, &Dummy);
	CalcCom(&Arc130, NULL, COL, &ComVolumeCol, &Dummy, &Dummy, &Dummy, &Dummy);
	
	/* Calculate the imbalance, making use of the fact that we only distributed the nonzeros over two processors. */
	MaxNrNz = MAX(Arc130.Pstart[2] - Arc130.Pstart[1], Arc130.Pstart[1] - Arc130.Pstart[0]);
	Imbalance = (double)(2*MaxNrNz - Arc130.NrNzElts)/(double)Arc130.NrNzElts;
	
	if (Imbalance > 0.03)
	{
		printf("Imbalance is too large!\n");
		return EXIT_FAILURE;
	}
	
	/* Display information about this partitioning. */
	printf("Succesfully distributed %ld nonzeros over two processors: %ld are assigned to processor 0 and %ld to processor 1.\n", Arc130.NrNzElts, Arc130.Pstart[1] - Arc130.Pstart[0], Arc130.Pstart[2] - Arc130.Pstart[1]);
	printf("This distribution has a total communication volume equal to %ld and imbalance equal to %.1f%%.\n", ComVolumeRow + ComVolumeCol, 100.0*Imbalance);
	
	/* Free matrix data. */
	MMDeleteSparseMatrix(&Arc130);
	
	return EXIT_SUCCESS;
}