Fmincon With internal calculations

Dear All

I was attempting to use the function fmincon to optimize a solution of a vessel design.My problem is the constraint equations contain some variables to be calculated first from the same design variables iterated by the fmincon function.In simple words i need the program to iterate 4 design variables but before going into the constraint functions to run some calculations to find some values used in the constraint equations.

Thanks

[Matt J]

Why do these intermediate variables have to be computed "before going into the constraint functions"? Why not compute them inside the constraint function, since they are also evolving with the optimization?