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solset := {x = -1, y = 2}, {x = 2, y = 1/2}
> assign (solset[1]); x,y;
-1,2
When there is a choice of solutions to assign, and you haven't specified a particular choice by
subscripting a particular solution in the set, assign will chose one solution to apply to the independent
variables.
You can make temporary assignments to mathematical variables using the function subs. This allows
you to evaluate an expression for a given set of values, without turning the mathematical variables into
programming variables. Given that Maple generally applies full evaluation, this is an important feature.
By giving subs a sequence of variable bindings and an expression, you can "test" the expression with
those values:
> # z is a programming variable:
> z;
z
> f := cos(z);
f := cos(z)
> # Now, to see what f(2) is:
> subs(z=Pi, f);
cos(Pi)
> # Force evaluation to simplify the result:
> eval(%);
-1
> # Now check to see the value of z:
> z;
z
11.3.9 Printing and Plotting Values (Drucken und Plotten)
When you give Maple a command, there is generally some form of expression that is the output, or
value, of the command. The "prettyprinted" output that you see is created by the Maple function print.
There are other forms of output that you can specify. These functions are:
• lprint: print the expression in a linear format
• fortran: print the expression according to Fortran 77 syntax
• eqn: create an eqn version of the expression for the troff document processor
• atex: generate a LaTeX description for the expression
Here is an example to show the difference between print and lprint:
> f := (a*b)/(c*d), c^d:
> print(f);
a b d
---, c
c d
> lprint(f);
a*b/c/d c**d
You can also plot expressions in Maple. Two-dimensional plots are generated using the plot
command, which works both in tty- and X-sessions. The basic syntax of the plot command is plot
(function, range), or plot (f(x), x=a..b). For instance:
> plot (cos(x), x = 0..Pi);
112