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Re: [Help-glpk] glp_get_col_prim() problem
From: |
Andrew Makhorin |
Subject: |
Re: [Help-glpk] glp_get_col_prim() problem |
Date: |
Thu, 22 Apr 2010 15:31:37 +0400 |
>> I'm having troubles while trying to get the solution variables via C
>> API. Below is the code I use in my program:
>
>> return (int) glp_get_col_prim(lp, i);
>
> Please note that glp_get_col_prim returns a floating-point value, so
> it would be better to write:
>
> return (int) (glp_get_col_prim(lp, i) + .5);
Yes, this may cause incorrect results. Imagine that x = 0.999999 due
to round-off errors in the simplex solver. Then
(int)x -> 0 (incorrect)
while
(int)(x + .5) -> 1 (correct)