Author 
Comment/Response 
Michael

04/28/10 10:43am
Consider the following lines of matheamtica code:
(* 1 *) Manipulate[Plot[Sin[a x], {x, 0, 2 Pi}], {a, 1, 2}]
Expr = Sin[a x];
(* 2 *) Manipulate[Plot[Expr, {x, 0, 2 Pi}], {a, 1, 2}]
(* 3 *) Manipulate[Expr /. x > Pi, {a, 1, 2}]
I want (* 2 *) to produce the same result as (* 1 *) but the variable 'a' is not being touched by Manipulate. However 'a' is manipulated in (* 3 *). Does anyone understand this problem. It seems like it has to do with the order in which variables are substituted.
The reason I care is that Expr may be a huge expression output from an ODE solver (which takes a long time to solve). I would like to precompute it, and plot it without having to copy and paste the expression in.
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