function y = calculate(func, x)
//
// given the name of some mathematical function, and a value 'x',
//   call the mathematical function with 'x' as an argument.
//   Return the resulting value.
//   
//   Arguments:
//   
//           func              (input)   the name of a Scilab  
//                                            function which we will call
//                                             
//           x                 (input)   value at which to evaluate the
//                                            function

  y = feval(x, func);

endfunction