I have been trying to write a model written originally in Mathematica, and I find that GAMS gives less precise solutions. The code below is a simplified version of a portion of the model. I am now trying to re-create my base, and it gives me a solutions that are a bit off: GAMS finds pc=2.151. It should be 3.61. 3.61 is the true price from our base data, and Mathematica is able to find this from the equations below. Is there a fix for this? Or an explanation of what is GAMS doing relative to Mathematica; so that I can explain the difference?

The difference in price is significant enough that my Prof. (who does not use GAMS), feels Mathematica is then a better solver…