# gaimc : Graph Algorithms In Matlab Code

### David Gleich (view profile)

Efficient pure-Matlab implementations of graph algorithms to complement MatlabBGL's mex functions.

prim_mst_perf.m
```%% Help debug prim_mst performance
%
profile off;
if exist('prof','var') && prof, profile on; end
nrep=15; mex_fast=0; mat_fast=0; mex_std=0; mat_std=0;
comp_results=[];
szs=[1 10000];
for szi=1:length(szs)
fprintf('\n%20s size=%-5i     ', 'mst_prim', szs(szi));
% Matlab needs 1 iteration to compile the function
if szi==2, mex_fast=0; mat_fast=0; mex_std=0; mat_std=0; end
for rep=1:nrep
fprintf('\b\b\b\b'); fprintf(' %3i', rep);
A=abs(sprandsym(szs(szi),25/szs(szi)));
At=A';
[rp ci ai]=sparse_to_csr(A); As.rp=rp; As.ci=ci; As.ai=ai;
tic; [t1i t1j t1v]=prim_mst(At,struct('istrans',1,'nocheck',1));
mex_fast=mex_fast+toc;
tic; [t2i t2j t2v]=mst_prim2(As,0); mat_fast=mat_fast+toc;
T1f=sparse(t1i,t1j,t1v,size(A,1),size(A,2));
T2f=sparse(t2i,t2j,t2v,size(A,1),size(A,2));
if ~isequal(T1f+T1f',T2f+T2f')
warning('gaimc:mst_prim',...
'incorrect results from mst_prim (%i,%i)', szi, rep);
fprintf('sum diff: %g\n', full(sum(sum(T1f))-sum(sum(T2f))));
fprintf('cmp diff: %10g %10g\n', ...
max(scomponents(T1f+T1f')), max(scomponents(T2f+T2f')));
keyboard
end
end
comp_results(end+1,:) = [mex_fast mat_fast];
end
fprintf('\n');
fprintf('mex time: %f\n', mex_fast);
fprintf('mat time: %f\n', mat_fast);
fprintf('\n');
if exist('prof','var') && prof, profile report; end
profile off;```