problem.getdf
problem.getdf |
Purpose
Get a distribution factor
Synopsis
value = problem.getdf(colindex, rowindex)
Arguments
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colindex
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The column (i.e.
xpress.var object, index, or name) whose distribution factor is to be retrieved.
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rowindex
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The row (i.e.
xpress.constraint object, index, or name) from which the distribution factor is to be taken.
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value
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The value of the distribution factor.
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Example
The following example retrieves the value of the distribution factor for column 282 in row 134 and changes it to be twice as large.
value = p.getdf(282,134) value *= 2 p.chgdf(282,134,calue)
Further information
The distribution factor of a column in a row is the matrix coefficient of the corresponding delta vector in the row. Distribution factors are used in conventional recursion models, and are essentially normalized first-order derivatives. Xpress SLP can accept distribution factors instead of initial values, provided that the values of the variables involved can all be calculated after optimization using determining rows, or by a callback.
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