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XPRSdelcols

Purpose
Delete columns from a matrix.
Topic area
Problem Creation
Synopsis
int XPRS_CC XPRSdelcols(XPRSprob prob, int ncols, const int colind[]);
Arguments
prob 
The current problem.
ncols 
Number of columns to delete.
colind 
Integer array of length ncols containing the columns to delete.
Example
In this example, column 3 is deleted from the matrix: 
colind[0] = 3;
XPRSdelcols(prob,1,colind);
Further information
1. After columns have been deleted from a problem, the numbers of the remaining columns are moved down so that the columns are always numbered from 0 to COLS-1 where COLS is the problem attribute containing the number of non-deleted columns in the matrix.
2. If the problem has already been optimized, or an advanced basis has been loaded, and you delete a basis column the current basis will no longer be valid - the basis is "lost".
If you go on to re-optimize the problem, a warning message is displayed ( 140) and the Optimizer automatically generates a corrected basis.
You can avoid losing the basis by only deleting non-basic columns (see XPRSgetbasis), taking a basic column out of the basis first if necessary (see XPRSgetpivots and XPRSpivot).
3. This function cannot be called while the current problem is being solved or when it is in an interrupted state. Use XPRSpostsolve to restore the problem to a non-solving state.
4. If a deleted column is referenced by a formula then it will be replaced by the constant 0 in that formula. If the formula is a PWL formula then instead an error is raised because the input column for a PWL must be a variable and cannot be a constant zero.
5. If a deleted column is referenced by a set then it will be removed from the set. Empty sets will not be deleted by this function.
6. If a column is referenced by a piecewise linear constraint then an attempt to delete it will raise an error.
7. If a column is referenced by a general constraint then an attempt to delete it will raise an error.
Related topics
XPRSaddcols, XPRSdelrows.

Parent Topic Console and Library Functions

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