@Carl Love  What i thought weird was that there were no more spaces between the eval and the parenthesis, when typing del or backspace it were removing the parenthesis or the "g" letter.

Thanks!

@Thomas Richard I wrote the equations in 2D.

and the procedure would become :

Note that the evalf has an "*" which was causing the trouble (I tried to change the 2D equation and i didnt get to remove the "*"), so i changed to 1D representation and then i removed the "*". Worked fine.

thanks both you!

 I am trying to solve a some differential equations that are interrelated. i use an written Runge-Kutta algorithm to solve them.

When i Debug i get the value given below. (kh1 is one of many parameters that i use into runge-kutta)

solv:
  26     kh1 := fh(r,y,h,t,t1,p,t3);

============================================
-.5257751014*evalf

Equation used to solve kh1:

when i disassemble this equation and i try to solve its pieces i get real numbers, so i think im not missing any parameters...

Is it possible i am missing some parameter ?