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bug from SALOME Forum (strange behaviour of StdMeshers.QUAD_REDUCED)

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avoid overflow at pow(2, nbrows) with a large nbrows
This commit is contained in:
eap 2011-06-20 10:49:58 +00:00
parent 646a140e47
commit 1d17d3304a
1 changed files with 9 additions and 6 deletions
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15
src/StdMeshers/StdMeshers_Quadrangle_2D.cxx
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@ -2218,9 +2218,9 @@ bool StdMeshers_Quadrangle_2D::ComputeReduced (SMESH_Mesh & aMesh,
int nrows = nr1 - 1; int nrows = nr1 - 1;
int ncol_top = nt1 - 1; int ncol_top = nt1 - 1;
int ncol_bot = nb1 - 1; int ncol_bot = nb1 - 1;
// maximum number of bottom elements for "tree" simple reduce 3->1 // number of rows needed to reduce ncol_bot to ncol_top using simple 3->1 "tree" (see below)
int max_tree31 = ncol_top * pow(3.0, nrows); int nrows_tree31 = int( log( ncol_bot / ncol_top ) / log( 3 )); // = log x base 3
if (ncol_bot > max_tree31) if ( nrows < nrows_tree31 )
MultipleReduce = true; MultipleReduce = true;
} }
@ -2543,9 +2543,12 @@ bool StdMeshers_Quadrangle_2D::ComputeReduced (SMESH_Mesh & aMesh,
// maximum number of bottom elements for "linear" simple reduce 4->2 // maximum number of bottom elements for "linear" simple reduce 4->2
int max_lin31 = ncol_top + ncol_top * 2 * nrows; int max_lin31 = ncol_top + ncol_top * 2 * nrows;
// maximum number of bottom elements for "tree" simple reduce 4->2 // maximum number of bottom elements for "tree" simple reduce 4->2
int max_tree42 = npair_top * pow(2.0, nrows + 1); int max_tree42 = 0;
if (ncol_top > npair_top * 2) { // number of rows needed to reduce ncol_bot to ncol_top using simple 4->2 "tree"
int delta = ncol_bot - max_tree42; int nrows_tree42 = int( log2( ncol_bot / ncol_top )); // needed to avoid overflow at pow(2)
if (ncol_top > npair_top * 2 && nrows_tree42 < nrows) {
max_tree42 = npair_top * pow(2.0, nrows + 1);
int delta = ncol_bot - int( max_tree42 );
for (int irow = 1; irow < nrows; irow++) { for (int irow = 1; irow < nrows; irow++) {
int nfour = delta / 4; int nfour = delta / 4;
delta -= nfour * 2; delta -= nfour * 2;