function mcr_run
  
%===============================================================================
% MATLAB MPMD EXAMPLE: RUNTIME CODE
%
% This function will be compiled by Matlab Compiler. This function
% - summarizes some configuration steps, e. g. defining dependencies
% - calls the Matlab function implemented by the user
%
% This function calls matmul_serial.m (matrix-matrix-multiplication with
% threading support) as dependency 1 and a plotting function as dependency 2.
%
% Each MPI process will run this code by evaluating its own rank.
%===============================================================================
 
 
%% =============================================================================
% Each process will use the MPI rank as task identifier.
% Get my MPI rank from the MPI environment.
%% =============================================================================
myrank = str2num(getenv('PMI_RANK'));
 
 
%% =============================================================================
% Create a log file for this task to avoid cluttered output of all MPI tasks in
% the Slurm job output file.
%% =============================================================================
fp = fopen(sprintf('data/JOB_%s_TaskID_%d.log', getenv('SLURM_JOB_ID'), myrank), 'w');
 
 
%===============================================================================
% All processes say hello.
% Show some information, also useful for troubleshooting
%===============================================================================
fprintf(fp, 'MPI process rank=%d: I run on compute node %s and will handle task %d.\n', ...
            myrank, getenv('HOSTNAME'), myrank);
fprintf(fp, 'MATLAB temporary directory = %s\n', tempdir);
fprintf(fp, 'MCR_CACHE_ROOT             = %s\n', getenv('MCR_CACHE_ROOT'));
fprintf(fp, 'MCR root dir               = %s\n', ctfroot);
 
 
%===============================================================================
% Run user code.
% Scale result by taskID to show MPMD effect.
%===============================================================================
% get sizes of input matrices for computation of C = A*B from commandline
% arguments
size_A = str2num(getenv('SIZE_MATRIX_A'));
size_B = str2num(getenv('SIZE_MATRIX_B'));
  
[C, comptime] = matmul_serial(size_A, size_B);
C = C * myrank;
fprintf(fp, '(rank=%d) computation time = %.4f s.\n', myrank, comptime);
fprintf(fp, '\tcheck (mean of elements scaled by MPI rank): %f\n', mean(C(:)));
fprintf('myrank=%d: check (mean of elements of C = A*B scaled by MPI rank): %f\n', myrank, mean(C(:)));
 
 
%% =============================================================================
% close log
%% =============================================================================
fclose(fp);