Equation Solver

Sometime ago I developed the following program (re-produced below) which returns the result of a mathmatical equation entered by a user. Any one who wishes to use this is welcome.

The equation can be entered as text
It can refer to variable names, the variable names must be stored in comma separated list and corresponding decimal values in an array.
It can use brackets
The equation can have intermediary value stored in variables invented by the user.

 
     E.g. of text entered by the user
 
 1.      A = X * .1.
         B = Y + Z.
         A / B.
 
 2.     (X * .i) / (Y + Z).

In both examples X and Y are variables, A and B are intermediate values that user wishes to create for clarity.

Usage.

Define the following shared variables

      Define new shared var ms-var as ch.
      Define new shared var ms-val as dec extent 500.
 
      ms-var = 'var1,var2,var3,......varn'.
      ms-val[1] = x ms-val[2] = y .... ms-val[n] = n.
      Run cal-eq.p(input equation-text,output result)

calc-eq.p contains the program script.