/* hull
Compute convex hull of a set of points
*/
void
hull(int nlhs, mxArray * plhs[], int nrhs, const mxArray * prhs[])
{
dd_PolyhedraPtr P;
dd_ErrorType err;
dd_MatrixPtr H,V;
dd_SetFamilyPtr GI,GA;
if (nrhs == 1 && nlhs <= 2 && mxIsStruct(prhs[0])) {
V = FT_get_V_MatrixPtr(prhs[0]);
dd_set_global_constants(); /* First, this must be called. */
P = dd_DDMatrix2Poly(V, &err); /* compute the second representation */
if (err == dd_NoError) {
H = dd_CopyInequalities(P);
plhs[0] = FT_set_H_MatrixPtr(H);
GI=dd_CopyIncidence(P);
GA=dd_CopyInputAdjacency(P);
plhs[1] = ZH_set_Vlist(GI,GA);
dd_FreeSetFamily(GI);
dd_FreeSetFamily(GA);
dd_FreeMatrix(H);
} else {
dd_WriteErrorMessages(stdout,err);
mexErrMsgTxt("CDD returned an error, see above(!) for details");
}
dd_FreeMatrix(V);
dd_FreePolyhedra(P);
return;
} else {
mexErrMsgTxt("hull expects a V input struct and produces an H output struct");
}
}
void allvertices(int m_input, int d_input, double *a_input)
/* output vertices and incidences */
{
dd_PolyhedraPtr poly;
dd_MatrixPtr A=NULL,G=NULL;
dd_SetFamilyPtr GI=NULL;
dd_rowrange i,m;
dd_colrange j,d;
dd_ErrorType err;
m=(dd_rowrange)m_input; d=(dd_colrange)d_input;
A=dd_CreateMatrix(m,d);
for (i=0; i<m; i++){
for (j=0; j<d; j++) dd_set_d(A->matrix[i][j],a_input[i*d+j]);
}
A->representation=dd_Inequality;
poly=dd_DDMatrix2Poly(A, &err);
/* compute the second (generator) representation */
if (err==dd_NoError) {
G=dd_CopyGenerators(poly);
GI=dd_CopyIncidence(poly);
MLPutFunction(stdlink,"List",2);
dd_MLWriteMatrix(G);
dd_MLWriteSetFamily(GI);
} else {
dd_MLWriteError(poly);
}
dd_FreeMatrix(A);
dd_FreeMatrix(G);
dd_FreeSetFamily(GI);
}
void allfacets(int n_input, int d_input, double *g_input)
/* output facets and incidences */
{
dd_PolyhedraPtr poly;
dd_MatrixPtr A=NULL,G=NULL;
dd_SetFamilyPtr AI=NULL;
dd_rowrange i,n;
dd_colrange j,d;
dd_ErrorType err;
n=(dd_rowrange)n_input; d=(dd_colrange)d_input;
G=dd_CreateMatrix(n,d);
for (i=0; i<n; i++){
for (j=0; j<d; j++) dd_set_d(G->matrix[i][j],g_input[i*d+j]);
}
G->representation=dd_Generator;
poly=dd_DDMatrix2Poly(G, &err);
/* compute the second (inequality) representation */
if (err==dd_NoError){
A=dd_CopyInequalities(poly);
AI=dd_CopyIncidence(poly);
MLPutFunction(stdlink,"List",2);
dd_MLWriteMatrix(A);
dd_MLWriteSetFamily(AI);
} else {
dd_MLWriteError(poly);
}
dd_FreeMatrix(A);
dd_FreeMatrix(G);
dd_FreeSetFamily(AI);
}
/*
* Find the extreme vertices between lower_bound and upper_bound of the convex
* hull of ineqs.
*
* ineqs: row-major order matrix of total length nrow*ncols
* nrows: Number of rows in matrix
* ncols: Number of columns in matrix
* lower_bound: lower bound of solution space on x-axis
* upper_bound: upper bound of solution space on y-axis
* output size: Set to size of result
*
* Returns array representing 3 by (output_size/3) matrix, where each row is:
* x_i, y_i, l_i
* Where x_i, y_i are the coordinates of the vertex, and l_i is the index of
* the input inequality that constrains the solution space *to the right* of
* vertex i.
*/
double *extreme_vertices(const double *ineqs, const size_t nrows,
const size_t ncols, float lower_bound,
float upper_bound, /*OUT*/ size_t * output_size)
{
/* Preconditions */
assert(ineqs != NULL);
assert(ncols == 3);
assert(output_size != NULL);
/* Check for approx equal lower and upper bound */
if (abs(lower_bound - upper_bound) < EPS)
return NULL;
assert(lower_bound <= upper_bound);
/*
* Initialize library
* TODO: Do we want to do this on every call?
*/
dd_set_global_constants();
dd_ErrorType err;
dd_MatrixPtr generators;
dd_MatrixPtr m =
init_ineq_doubles(ineqs, nrows, ncols, lower_bound, upper_bound);
dd_SetFamilyPtr incidence;
/* Outputs */
dd_PolyhedraPtr poly = dd_DDMatrix2Poly(m, &err);
if (err != dd_NoError) {
return NULL;
}
/* Get generators */
generators = dd_CopyGenerators(poly);
/* Get incidence */
incidence = dd_CopyIncidence(poly);
double *result =
list_extreme_vertices(generators, incidence, nrows, m->rowsize - 1,
output_size);
dd_FreeMatrix(m);
dd_FreeMatrix(generators);
dd_FreePolyhedra(poly);
dd_FreeSetFamily(incidence);
dd_free_global_constants();
return result;
}
