Imposing Summation Constraints
 

I am currently attempting to implement automatic edge meshing using a hyperbolic tangental function, (ie: Y=a*tanh(X)+b, where Y=spacing along X) By using X(1),X(N),Y(1),Y(N) as boundary conditions the routine I have works fine. The problem is that I need to add the constraint: sum(Y)=X(N)-X(1). Any Suggestions on how to accomplish this? My feelings at this point are that an iterative method should be used.