/* Demo of macsyma substitution macros. */

if get('submac,'version)=false
then load('submac)$

/* define a macro to compute a numerical integration. 
   We want it to take an expression, a variable, and upper and
   lower limits. The expression will be evaluated for values
   of the variable between the upper and lower limits. */

rect_rule('exp,'x,a,b,dx)=>
 (modedeclare([a,b,dx],float),
  block([%_sum:0.0],modedeclare(%_sum,float),
        for x:a thru b step dx do %_sum:%_sum+exp,
	dx*%_sum))$

grind(rect_rule);

define(g(a),macroexpand(rect_rule(x^2,x,0.0,a,0.1)))$
grind(g);