Evaluator

EVALUATOR


by William Fraser





If you've ever tried to write a program that deals with mathematical


equations and other such complicated number thingies, it may have


occurred to you that there's no obvious way of actually getting the


equations into the computer (unless you actually build them Into the


program to start off with of course, which isn't much use).





It would be much handier if there was a way of getting our


rubber-keyed chum to ask you to type in equations while the program's


running, but unfortunately there isn't. Or, that is, there wasn't.


(Bet you weren't expecting that.)





By using William Fraser's routine all you've got to do is INPUT the


equation into Z$ and then RANDOMIZE USR 64000. The routine then calls


the appropriate ROM routine to evaluate the equation and returns the


answer in the variable y.





As a special added bonus William's incorporated the routine into a


graph- plotting program so you can see exactly what's going on. All


you've got to do is type in the Basic listing (missing out all the


instructions if you want, of course) and save it onto tape.





Then simply fish out the Hex Loader from a previous YS (the November


issue would do fine) and use it to type in the hex listing, which


should be saved after the Basic. Reload, run and you're away.