get_lambda, get_ptr_lambda

Returns the Lamdba vectors (Lagrangian optimization).

unsigned char get_lambda(lprec *lp, REAL *lambda);

unsigned char get_ptr_lambda(lprec *lp, REAL **ptr_lambda);

Return Value

get_lambda, get_ptr_lambda returns TRUE (1) if the operation was successful. A return value of FALSE (0) indicates an error.



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


An array that will contain the values of the Lamdba vectors.


The address of a pointer that will point to an array that will contain the values of the Lamdba vectors.


The get_lambda, get_ptr_lambda functions retrieve the Lamdba vectors.
These values are only valid after a successful lag_solve. Function get_lambda needs an array that is already dimensioned with get_Lrows elements. get_ptr_lambda returns a pointer to an array already dimensioned by lp_solve.

Note that get_ptr_lambda returns a pointer to memory allocated and maintained by lp_solve. Be careful what you do with it. Don't modify its contents or free the memory. Unexpected behaviour would occur. Also note that this memory pointer is only guaranteed to remain constant until a next lp_solve API call is done. You should call this function again to make sure you have again the correct pointer. Otherwise, this pointer could point to invalid memory. This should not be a problem since this call is very efficient.


#include <stdio.h>
#include <stdlib.h>
#include "lp_lib.h"

int main(void)
  lprec *lp;
  int ret;
  REAL row[1+2]; /* must be 1 more then number of columns ! */
  REAL *ptr_lambda, lambda[1];

  /* Create a new LP model */
  lp = make_lp(0, 0);
  if(lp == NULL) {
    fprintf(stderr, "Unable to create new LP model\n");

  row[1] = 1.0;
  row[2] = 1.0;
  add_lag_con(lp, row, LE, 1.0);

  ret = lag_solve(lp, 0, 30, FALSE);

  get_lambda(lp, lambda);
  get_ptr_lambda(lp, &ptr_lambda);


lp_solve API reference

See Also make_lp, read_lp, read_LP, read_mps, read_freemps, read_MPS, read_freeMPS, read_XLI, is_feasible, get_objective, get_working_objective, get_variables, get_ptr_variables, get_primal_solution, get_ptr_primal_solution, get_var_primalresult, get_sensitivity_rhs, get_ptr_sensitivity_rhs, get_dual_solution, get_ptr_dual_solution, get_var_dualresult, get_sensitivity_obj, get_ptr_sensitivity_obj, get_sensitivity_objex, get_ptr_sensitivity_objex, get_constraints, get_ptr_constraints, lag_solve