XSLPloadcoefs, XPRSslploadcoefs

Purpose

Load non-linear coefficients into the SLP problem. For a simpler version of this function see XSLPloadformulas.

Topic areas

Synopsis

int XPRS_CC XSLPloadcoefs(XSLPprob prob, int ncoefs, const int[] rowind, const int[] colind, const double[] factor, const int[] formulastart, int parsed, const int[] type, const double[] coef);

Arguments

prob	The current SLP problem.
ncoefs	Number of non-linear coefficients to be loaded.
rowind	Integer array holding index of row for the coefficient.
colind	Integer array holding index of column for the coefficient.
factor	Double array holding factor by which formula is scaled. If this is NULL, then a value of 1.0 will be used.
formulastart	Integer array of length ncoefs+1 holding the start position in the arrays type and coef of the formula for the coefficients. formulastart[ncoefs] should be set to the next position after the end of the last formula.
parsed	Integer indicating whether the token arrays are formatted as internal unparsed ( parsed=0) or internal parsed reverse Polish ( parsed=1).
type	Array of token types providing the formula for each coefficient.
coef	Array of values corresponding to the types in type.

Example

Assume that the rows and columns of prob are named Row1, Row2 ..., Col1, Col2 ... The following example loads coefficients representing:
Col2 * Col3 + Col6 * Col2 ˆ2 into Row1 and
Col2 ˆ 2 into Row3.

int rowind[3], colind[3], formulastart[4], type[8];
int n, ncoefs;
double coef[8];

rowind[0] = 1; colind[0] = 2;
rowind[1] = 1; colind[1] = 6;
rowind[2] = 3; colind[2] = 2;

n = ncoefs = 0;
formulastart[ncoefs++] = n;
type[n] = XSLP_COL; coef[n++] = 3;
type[n++] = XSLP_EOF;

formulastart[ncoefs++] = n;
type[n] = XSLP_COL; coef[n++] = 2;
type[n] = XSLP_COL; coef[n++] = 2;
type[n] = XSLP_OP;  coef[n++] = XSLP_MULTIPLY;
type[n++] = XSLP_EOF;

formulastart[ncoefs++] = n;
type[n] = XSLP_COL; coef[n++] = 2;
type[n++] = XSLP_EOF;

formulastart[ncoefs] = n;

XSLPloadcoefs(prob, ncoefs, rowind, colind,
             NULL, formulastart, 1, type, coef);

The first coefficient in Row1 is in Col2 and has the formula Col3, so it represents Col2 * Col3.

The second coefficient in Row1 is in Col6 and has the formula Col2 * Col2 so it represents Col6 * Col2 ˆ2. The formulae are described as parsed (parsed=1), so the formula is written as
Col2 Col2 *
rather than the unparsed form
Col2 * Col2

The last coefficient, in Row3, is in Col2 and has the formula Col2, so it represents Col2 * Col2.

Further information

1. The j ^th coefficient is made up of two parts: factor and Formula. factor is a constant multiplier, which can be provided in the factor array. If Xpress NonLinear can identify a constant factor in Formula, then it will use that as well, to minimize the size of the formula which has to be calculated. Formula is made up of a list of tokens in type and coef starting at formulastart[j]. The tokens follow the rules for parsed or unparsed formulae as indicated by the setting of parsed. The formula must be terminated with an XSLP_EOF token. If several coefficients share the same formula, they can have the same value in formulastart. For possible token types and values see the chapter on Xpress NonLinear Formulae.

2. The load functions load items into the SLP problem. Any existing items of the same type are deleted first. The corresponding add functions add or replace items leaving other items of the same type unchanged.

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Glossary

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XSLPloadcoefs, XPRSslploadcoefs