Memory problems using mathlink (Sparse Matrix)

*To*: mathgroup at smc.vnet.net*Subject*: [mg24252] Memory problems using mathlink (Sparse Matrix)*From*: Martin Zacho <zac at mip.sdu.dk>*Date*: Tue, 4 Jul 2000 15:22:13 -0400 (EDT)*Organization*: UNI-C*Sender*: owner-wri-mathgroup at wolfram.com

Hi, I'm doing some rather big matrixcomputations in C and would like to solve the problem using mathematica. The (sparse) matrix is about 4 millions doubles and I'm using the following form: {{...},{{i,j}->A[i][j],...},{...}} The relevant MathLink part of the program is as follows: ....do some rather long and booring calculations... MLPutFunction(stdlink, "List", 2); MLPutFunction(stdlink, "List", M); for (j=0; j<M; j++) { MLPutFunction(stdlink, "List", no[j]); for (k=0; k<M; k++) { MLPutFunction(stdlink, "Rule", 2); MLPutFunction(stdlink, "List", 2); MLPutInteger(stdlink, j+1); MLPutInteger(stdlink, k+1); MLPutReal(stdlink, BigMatrix[i][j]); } } MLPutRealList(stdlink, y, M); ....clean up memory... I'm also transfeering a small list of length M (approx. 8000 doubles). The matrix is a MxM matrix with numbers in approx 7% of the cells. The data structures occupies approx. 90MB in C but when they are transfered to mathematica, MathKernel uses a _lot_ of memory (>500MB). This causes 'my' machine to crash for some odd reason even though it has 8GB of RAM and 6GB of swap. The machine is a SUN running Solaris. The kernel is version 4.0 release 2. My problem: How can I reduce memory req. ? Am I doing anything wrong ? Sincerely, Martin Zacho