void simplex(Tableau *tab) {
int loop=0;
add_slack_variables(tab);
check_b_positive(tab);
print_tableau(tab,"Padded with slack variables");
while( ++loop ) {
int pivot_col, pivot_row;
pivot_col = find_pivot_column(tab);
if( pivot_col < 0 ) {
printf("Found optimal value=A[0,0]=%3.2lf (no negatives in row 0).\n",
tab->mat[0][0]);
print_optimal_vector(tab, "Optimal vector");
break;
}
printf("Entering variable x%d to be made basic, so pivot_col=%d.\n",
pivot_col, pivot_col);
pivot_row = find_pivot_row(tab, pivot_col);
if (pivot_row < 0) {
printf("unbounded (no pivot_row).\n");
break;
}
printf("Leaving variable x%d, so pivot_row=%d\n", pivot_row, pivot_row);
pivot_on(tab, pivot_row, pivot_col);
print_tableau(tab,"After pivoting");
print_optimal_vector(tab, "Basic feasible solution");
if(loop > 20) {
printf("Too many iterations > %d.\n", loop);
break;
}
}
}
unsigned int simplex(const int m, const int n, lp_t * p) {
// init DFE
max_file_t * maxfile = Simplex_init();
max_engine_t * engine = max_load(maxfile, "*");
// align for streaming
int align_m, align_n;
lp_t * align_p = copy_aligned(m, n, p, &align_m, &align_n);
if (trace > 0) printf("aligned: %dx%d -> %dx%d\n", m, n, align_m, align_n);
// reserve buffers
lp_t * pivcol = (lp_t *) malloc(align_m * sizeof(lp_t));
lp_t * pivrow = (lp_t *) malloc(align_n * sizeof(lp_t));
// Simplex action to call DFE
Simplex_actions_t act;
act.param_m = align_m;
act.param_n = align_n;
act.instream_pivcol = pivcol;
act.instream_pivrow = pivrow;
act.instream_x = align_p;
act.outstream_y = align_p;
// main loop
unsigned int count = 0;
while (count < max_iterations || max_iterations == 0) {
// column
int col = pivot_rule == 0 ? find_pivot_column_first(align_n, align_p) : find_pivot_column_max(align_n, align_p);
if (col < 0) break; // optimum found
// row
int row = find_pivot_row(align_m, align_n, align_p, col);
if (row < 0) { align_p[0] = NAN; break; } // unbounded
// pivoting
count++;
lp_t pivot = align_p[row * align_n + col];
if (trace > 0) printf("%d: pivoting on %d, %d: %"lp_t_fmt1"\n", count, row, col, pivot);
// store pivcol & pivrow for DFE streaming
for (int i = 0; i < align_m; i++) pivcol[i] = align_p[i * align_n + col];
for (int j = 0; j < align_n; j++) pivrow[j] = align_p[row * align_n + j];
// call DFE for pivoting
act.param_row = row;
act.param_col = col;
act.param_pivot = 1 / pivot;
Simplex_run(engine, &act);
// tracing
if (trace >= 9) write_bg(stdout, m, n, p);
if (trace >= 2) print_obj(n, p);
if (trace >= 3) print_bounds(m, n, p);
}
// unload DFE
max_unload(engine);
// free buffers
free(pivcol);
free(pivrow);
p[0] = align_p[0];
return count;
}
static void perform_partial_pivot(matrix_t * A, vector_t * b, int k)
{
int pivot_row = find_pivot_row(A, k, k);
double * tmp,
tmp_d;
if (pivot_row == k) {
return; /* no need to pivot */
}
/* swap the pivot row and the current */
tmp = A->data[pivot_row];
A->data[pivot_row] = A->data[k];
A->data[k] = tmp;
tmp_d = b->data[pivot_row];
b->data[pivot_row] = b->data[k];
b->data[k] = tmp_d;
}
unsigned int simplex(const int m, const int n, lp_t * p) {
// init DFE
max_file_t * maxfile = Simplex_init();
max_engine_t * engine = max_load(maxfile, "*");
// align for streaming
int align_m, align_n;
lp_t * align_p = copy_aligned(m, n, p, &align_m, &align_n);
if (trace > 0) printf("aligned: %dx%d -> %dx%d\n", m, n, align_m, align_n);
// reserve buffers
lp_t * c = malloc(align_n * sizeof(lp_t));
lp_t * ratio = malloc(align_m * sizeof(lp_t));
lp_t * pivcol = malloc(align_m * sizeof(lp_t));
lp_t * pivrow = malloc(align_n * sizeof(lp_t));
// init buffers: c, ratio, pivcol, pivrow
for (int j = 0; j < n; j++) c[j] = p[j];
uint64_t col = find_pivot_column_max(n, c);
for (int i = 0; i < align_m; ++i) {
pivcol[i] = align_p[i * align_n + col];
ratio[i] = align_p[i * align_n] / pivcol[i];
}
int row = find_pivot_row(m, ratio);
for (int i = 0; i < align_n; i++) pivrow[i] = align_p[row * align_n + i];
// write LP to LMem
Simplex_writeLMem_actions_t writeact;
writeact.param_address = 0;
writeact.param_count = align_m * align_n;
writeact.instream_tolmem = align_p;
Simplex_writeLMem_run(engine, &writeact);
// simplex action to call DFE
Simplex_actions_t act;
act.param_m = align_m;
act.param_n = align_n;
act.instream_pivcol = pivcol;
act.instream_pivrow = pivrow;
act.outscalar_MaxKernel_maxcol_out = &col;
act.outstream_ratio_out = ratio;
act.outstream_pivcol_out = pivcol;
act.outstream_c_out = c;
// main loop
unsigned int count = 0;
while (count < max_iterations || max_iterations == 0) {
// read pivot row from lmem
Simplex_readLMem_actions_t readact;
readact.param_address = row * align_n;
readact.param_count = align_n;
readact.outstream_fromlmem = pivrow;
Simplex_readLMem_run(engine, &readact);
// pivoting,max,filter
count++;
lp_t pivot = pivrow[col];
if (trace > 0) printf("%u: pivoting on %d, %lu: %g\n", count, row, col, pivot);
act.param_pivot = 1 / pivot;
act.param_col = col;
act.param_row = row;
Simplex_run(engine, &act);
ratio[0] = -1;
pivcol[0] = c[col];
//if (trace >= 9) write_bg(stdout, m, n, p);
if (col <= 0) break; // optimum found
// row
row = find_pivot_row(m, ratio);
if (row < 0) { p[0] = NAN; break; } // unbounded
}
// unload DFE
max_unload(engine);
// return results (TODO: copy full lp from lmem to p)
p[0] = c[0];
// free buffers
free(c);
free(ratio);
free(pivcol);
free(pivrow);
return count;
}
