Variable use between CAS and Home.

[Han]

From Home to CAS:

Suppose you have a formula entered in F1 (using Plot app). So if F1 is defined as X^2+4*X-5, then in the CAS, you can simply do:

purge(x);
f:=F1(x);
factor(f);

This creates an expression named f with dummy variable x; i.e. f is the same as x^2+4*x-5 (in lower case). The right hand side is an evaluation of the function F1 at x. You can then work with the expression using f in its place rather than having to copy/paste or type out the expression.

From CAS to Home:

Suppose you have x^2+4*x-5 on your screen at some point. To quickly apply this formula to F1, type:

F1:=x->

and with the cursor sitting after the > symbol in the command line, use your touchscreen to copy the formula to complete the command as:

F1:=x->x^2+4*x-5;

This creates a function objection with dummy variable x and formula x^2+4*x-5; the calculator will "automagically" convert lower case x to upper case X for you.

Notes:

You could have also created a function f using f:=F1. To then obtain an expression, you can then use functional notation to evaluate f at the variable x by typing: f(x).

Thus f:=F1; followed by factor(f(x)); would also have worked for the Home to CAS case.