I think there's a bug in the FEQParse (Fortran Equation Parser) program. Using the example 'scalar_with_scalar_eval.f90', I get different results depending on the order of the components:

y = x-sqrt(x)+100

   x                    y

0.000000 -100.0000

4.000000 -98.00000

y = -sqrt(x)+100+x

   x                    y

0.000000 100.0000

4.000000 102.0000

I am using the latest available version of FEQParse.