set_pivoting
Sets the pivot rule and mode.
void set_pivoting(lprec *lp, int pivoting);
Return Value
set_pivoting has no return value.
Parameters
lp
Pointer to previously created lp model. See return value of
make_lp, copy_lp, read_lp,
read_LP, read_mps, read_freemps, read_MPS, read_freeMPS, read_XLI
pivoting
The pivot rule and mode. Can be one of the following rules:
PRICER_FIRSTINDEX (0) 
Select first 
PRICER_DANTZIG (1) 
Select according to Dantzig 
PRICER_DEVEX (2) 
Devex pricing from Paula Harris 
PRICER_STEEPESTEDGE (3) 
Steepest Edge 
Some of these values can be combined with any (ORed) of the following modes:
PRICE_PRIMALFALLBACK (4) 
In case of Steepest Edge, fall back to DEVEX in primal 
PRICE_MULTIPLE (8) 
Preliminary implementation of the multiple pricing scheme. This means that
attractive candidate entering columns from one iteration may be used in the
subsequent iteration, avoiding full updating of reduced costs. In the current
implementation, lp_solve only reuses the 2nd best entering column alternative 
PRICE_PARTIAL (16) 
Enable partial pricing 
PRICE_ADAPTIVE (32) 
Temporarily use alternative strategy if cycling is detected 
PRICE_RANDOMIZE (128) 
Adds a small randomization effect to the selected pricer 
PRICE_AUTOPARTIAL (512) 
Indicates automatic detection of segmented/staged/blocked models. It refers to
partial pricing rather than full pricing. With full pricing, all nonbasic
columns are scanned, but with partial pricing only a subset is scanned for every
iteration. This can speed up several models 
PRICE_LOOPLEFT (1024) 
Scan entering/leaving columns left rather than right 
PRICE_LOOPALTERNATE (2048) 
Scan entering/leaving columns alternatingly left/right 
PRICE_HARRISTWOPASS (4096) 
Use Harris' primal pivot logic rather than the default 
PRICE_TRUENORMINIT (16384) 
Use true norms for Devex and Steepest Edge initializations 
Remarks
The set_pivoting function specifies the pivot rule (rule for selecting row
and column entering/leaving) and mode. The rule is an exclusive option and the mode
is a modifier to the rule. This rule/mode can influence solving times
considerably. Depending on the model one rule/mode can be best and for another model
another rule/mode.
The default is PRICER_DEVEX  PRICE_ADAPTIVE (34).
Example
#include <stdio.h>
#include <stdlib.h>
#include "lp_lib.h"
int main(void)
{
lprec *lp;
/* Create a new LP model */
lp = make_lp(0, 0);
if(lp == NULL) {
fprintf(stderr, "Unable to create new LP model\n");
return(1);
}
set_pivoting(lp, PRICER_FIRSTINDEX);
delete_lp(lp);
return(0);
}
lp_solve API reference
See Also make_lp, copy_lp,
read_lp, read_LP, read_mps,
read_freemps, read_MPS, read_freeMPS, read_XLI, get_pivoting, is_piv_rule, is_piv_mode
