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# problem.loadMIQP

Purpose
Used to load a MIQP problem, hence a MIP with quadratic objective coefficients, into the Optimizer data structures. Integer, binary, partial integer, semi-continuous and semi-continuous integer variables can be defined, together with sets of type 1 and 2. The reference row values for the set members are passed as an array rather than specifying a reference row.
Topic areas
Problem Input, Quadratic, Optimizer
Synopsis
`problem.loadMIQP(probname="", rowtype=None, rhs=None, rng=None, objcoef=None, start=None, collen=None, rowind=None, rowcoef=None, lb=None, ub=None, objqcol1=None, objqcol2=None, objqcoef=None, coltype=None, entind=None, limit=None, settype=None, setstart=None, setind=None, refval=None)`
Arguments

probname | A string of up to MAXPROBNAMELENGTH characters containing a name for the problem. If probname is None, the problem name will be an empty string.
rowtype | Character array containing the row type:
L | indicates a ≤ constraint;
E | indicates an = constraint;
G | indicates a ≥ constraint;
R | indicates a range constraint;
N | indicates a nonbinding constraint.
May be None if the problem contains no rows.
rhs | Double array 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. May be None if the problem contains no rows.
rng | Double array containing the range values for range rows. The values in the range array will only be read for R type rows. The entries for other type rows will be ignored. May be None 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.
objcoef | Double array containing the objective function coefficients. This can be None to set all objective coefficients to 0 (zero).
start | Integer array containing the offsets in the rowind and rowcoef arrays of the start of the elements for each column. This array contains one entry for each column, plus one more if collen is None. If collen is None, the last entry of start contains the position in the rowind and rowcoef arrays at which an extra column would start, if it were present. This value is also the length of the rowind and rowcoef arrays. May be None if the problem contains no coefficients.
collen | Integer array containing the number of nonzero elements in each column. May be None if not required. This array is not required if the non-zero coefficients in the rowind and rowcoef arrays are contiguous, and the start array has an additional entry as described above.
rowind | Integer array containing the row indices for the nonzero elements in each column. May be None if the problem contains no coefficients. If the indices are input contiguously, with the columns in ascending order, the length of the rowind array is found by adding the start entry for the last column to the collen entry for the last column, or if collen is None, by the additional entry at the end of start.
rowcoef | Double array containing the nonzero element values; length as for rowind. May be None if the problem contains no coefficients.
lb | Double array containing the lower bounds on the columns. Use -xpress.infinity to represent a lower bound of minus infinity. If this is None then all lower bounds are 0 (zero).
ub | Double array containing the upper bounds on the columns. Use xpress.infinity to represent an upper bound of plus infinity. If this is None then all upper bounds are infinite.
objqcol1 | Integer array containing the column index of the first variable in each quadratic term. May be None if all objective coefficients are zero.
objqcol2 | Integer array containing the column index of the second variable in each quadratic term. May be None if all objective coefficients are zero.
objqcoef | Double array containing the quadratic coefficients. May be None if all objective coefficients are zero.
coltype | Character array containing the entity types:
B | binary variables;
I | integer variables;
P | partial integer variables;
S | semi-continuous variables;
R | semi-continuous integers.
May be None if all variables are continuous.
entind | Integer array containing the column indices of the MIP entities. May be None if the problem contains no entities.
limit | Double array containing the integer limits for the partial integer variables and lower bounds for semi-continuous and semi-continuous integer variables (any entries in the positions corresponding to binary and integer variables will be ignored). May be None if not required.
settype | Character array containing:
1 | SOS1 type sets;
2 | SOS2 type sets.
May be None if not required.
setstart | Integer array containing the offsets in the setind and refval arrays indicating the start of each set. This array has one entry for each set plus one extra entry containing the offset where an additional set would start, if it were present. May be None if not required.
setind | Integer array containing the columns in each set. May be None if not required.
refval | Double array containing the reference row entries for each member of the sets. These define the order for SOS2 constraints and may be used in branching for both types. May be None if not required.

Related controls
Integer

EXTRACOLS | Number of extra columns to be allowed for.
EXTRAELEMS | Number of extra matrix elements to be allowed for.
EXTRAMIPENTS | Number of extra MIP entities to be allowed for.
EXTRAROWS | Number of extra rows to be allowed for.
KEEPNROWS | Status for nonbinding rows.
SCALING | Type of scaling.

Double

MATRIXTOL | Tolerance on matrix elements.
SOSREFTOL | Minimum gap between reference row entries.

Further information
1. The objective function is of the form c'x+ 0.5 x'Qx. Note that only the upper or lower triangular part of the Q matrix is specified.
2. The double constants xpress.infinity and -xpress.infinity are defined in the Optimizer library header file.
3. Passing zero for all integer arguments and None for all array arguments will load an empty problem.
4. Argument rowind may contain xpress.constraint objects instead of indices.
5. Arguments objqcol1, objqcol2, entind, setind may contain xpress.var objects instead of indices.
Related topics
problem.loadMIP, problem.loadLP, problem.loadQP, problem.readProb.
Parent Topic Methods of the class problem

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