Procedure GMP::Column::SetLowerBound(GMP, column, value)

GMP::Column::SetLowerBound

The procedure GMP::Column::SetLowerBound changes the lower bound of a column in a generated mathematical program.

GMP::Column::SetLowerBound(
     GMP,            ! (input) a generated mathematical program
     column,         ! (input) a scalar reference or column number
     value           ! (input) a numerical expression
     )

Arguments

GMP

An element in AllGeneratedMathematicalPrograms.

column

A scalar reference to an existing column in the matrix or an element in the set Integers in the range \(\{ 0 .. n-1 \}\) where \(n\) is the number of columns in the matrix.

value

The new value assigned to the lower bound of the column.

Return Value

The procedure returns 1 on success, and 0 otherwise.

Note

• Use GMP::Column::SetLowerBoundMulti or GMP::Column::SetLowerBoundRaw if the lower bounds of many columns have to be set, because that will be more efficient.

• If the column has a unit then value should have the same unit. If value has no unit then you should multiply it by the column scale, as returned by the function GMP::Column::GetScale.

Example

Assume that ‘x1’ is a variable in mathematical program ‘MP’ with a unit as defined by:

Quantity SI_Mass {
    BaseUnit      :  kg;
    Conversions   :  ton -> kg : # -> # * 1000;
}
Parameter min_wght {
    Unit          :  ton;
    InitialValue  :  20;
}
Variable x1 {
    Range         :  [min_wght, inf);
    Unit          :  ton;
}

Then if we run the following code

GMP::Column::SetLowerBound( 'MP', x1, 20 [ton] );
lb1 := GMP::Column::GetLowerBound( 'MP', x1 );
display lb1;

GMP::Column::SetLowerBound( 'MP', x1, 30 );
lb2 := GMP::Column::GetLowerBound( 'MP', x1 );
display lb2;

GMP::Column::SetLowerBound( 'MP', x1, 40 * GMP::Column::GetScale( 'MP', x1 ) );
lb3 := GMP::Column::GetLowerBound( 'MP', x1 );
display lb3;

(where ‘lb1’, ‘lb2’ and ‘lb3’ are parameters without a unit) we get the following results:

lb1 := 20 ;

lb2 := 0.030 ;

lb3 := 40 ;

See also

The routines GMP::Instance::Generate, GMP::Column::SetLowerBoundMulti, GMP::Column::SetLowerBoundRaw, GMP::Column::SetUpperBound, GMP::Column::GetLowerBound and GMP::Column::GetScale.