set_pivoting

Sets the pivot rule and mode.

void set_pivoting(lprec *lp, int pivoting);

Return Value

set_pivoting has no return value.

Parameters

Pointer to previously created lp model. See return value of make_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.ï¿½This means that attractive candidate entering columnsï¿½from one iteration may be used in the subsequent iteration, avoiding full updating of reduced costs.ï¿½ 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 First Index if cycling is detected
PRICE_RANDOMIZE (128)	Adds a small randomization effect to the selected pricer
PRICE_LOOPLEFT (1024)	Scan entering/leaving columns left rather than right
PRICE_LOOPALTERNATE (2048)	Scan entering/leaving columns alternatingly left/right

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