XPRSloadlp, XPRSloadlp64
XPRSloadlp, XPRSloadlp64 |
Purpose
Enables the user to pass a
matrix directly to the
Optimizer, rather than reading the matrix from a file.
Synopsis
int XPRS_CC XPRSloadlp(XPRSprob prob, const char *probname, int ncol, int nrow, const char qrtype[], const double rhs[], const double range[], const double obj[], const int mstart[], const int mnel[], const int mrwind[], const double dmatval[], const double dlb[], const double dub[]);
int XPRS_CC XPRSloadlp64(XPRSprob prob, const char *probname, int ncol, int nrow, const char qrtype[], const double rhs[], const double range[], const double obj[], const XPRSint64 mstart[], const int mnel[], const int mrwind[], const double dmatval[], const double dlb[], const double dub[]);
Arguments
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prob
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The current problem.
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probname
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A string of up to
MAXPROBNAMELENGTH characters containing a names for the problem.
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ncol
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Number of structural columns in the matrix.
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nrow
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Number of rows in the matrix (not including the objective). Objective coefficients must be supplied in the
obj array, and the objective function should not be included in any of the other arrays.
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qrtype
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Character array of length
nrow containing the row types:
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rhs
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Double array of length
nrow containing the right hand side coefficients of the rows. The right hand side value for a range row gives the
upper bound on the row.
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range
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Double array of length
nrow containing the range values for range rows. Values for all other rows will be ignored. May be
NULL if not required. The lower bound on a range row is the right hand side value minus the range value. The sign of the range value is ignored - the absolute value is used in all cases.
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obj
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Double array of length
ncol containing the objective function coefficients.
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mstart
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Integer array containing the offsets in the
mrwind and
dmatval arrays of the start of the elements for each column. This array is of length
ncol or, if
mnel is
NULL, length
ncol+1. If
mnel is
NULL, the extra entry of
mstart,
mstart[ncol], contains the position in the
mrwind and
dmatval arrays at which an extra column would start, if it were present. In C, this value is also the length of the
mrwind and
dmatval arrays.
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mnel
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Integer array of length
ncol containing the number of nonzero elements in each column. May be
NULL if not required. This array is not required if the non-zero coefficients in the
mrwind and
dmatval arrays are continuous, and the
mstart array has
ncol+1 entries as described above.
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mrwind
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Integer array containing the row indices for the nonzero elements in each column. If the indices are input contiguously, with the columns in ascending order, the length of the
mrwind is
mstart[ncol-1]+mnel[ncol-1] or, if
mnel is
NULL,
mstart[ncol].
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dmatval
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Double array containing the nonzero element values; length as for
mrwind.
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dlb
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Double array of length
ncol containing the lower bounds on the columns. Use
XPRS_MINUSINFINITY to represent a lower bound of minus infinity.
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dub
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Double array of length
ncol containing the upper bounds on the columns. Use
XPRS_PLUSINFINITY to represent an upper bound of plus infinity.
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Related controls
Integer
Double
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Number of extra columns to be allowed for.
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Number of extra matrix elements to be allowed for.
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Number of extra elements to allow for in presolve.
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Number of extra rows to be allowed for.
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Status for nonbinding rows.
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Type of scaling.
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Double
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Tolerance on matrix elements.
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Example
Given an LP problem:
the following shows how this may be loaded into the Optimizer using
XPRSloadlp:
| maximize: | x + y | ||
| subject to: | 2x | ≥ | 3 |
| x + 2y | ≥ | 3 | |
| x + y | ≥ | 1 |
char probname[] = "small";
int ncol = 2, nrow = 3;
char qrtype[] = {'G','G','G'};
double rhs[] = { 3 , 3 , 1 };
double obj[] = { 1 , 1 };
int mstart[] = { 0 , 3 , 5 };
int mrwind[] = { 0 , 1 , 2 , 1 , 2 };
double dmatval[] = { 2 , 1 , 1 , 2 , 1 };
double dlb[] = { 0 , 0 };
double dub[] = {XPRS_PLUSINFINITY,XPRS_PLUSINFINITY};
XPRSloadlp(prob, probname, ncol, nrow, qrtype, rhs, NULL,
obj, mstart, NULL, mrwind, dmatval, dlb, dub)
Further information
1. The row and column indices follow the usual C convention of going from
0 to
nrow-1 and
0 to
ncol-1 respectively.
2. The double constants
XPRS_PLUSINFINITY and
XPRS_MINUSINFINITY are defined in the Optimizer library header file.
3. For a range constraint, the value in the
rhs array specifies the upper bound on the constraint, while the value in the
range array specifies the range on the constraint. So a range constraint
j is interpreted as:
rhsj-|rangej| ≤
aijxi ≤ rhsj
| ∑ |
| i |
Related topics