Thank you guys. I finnally got it works (in Maple 11). In my case I don't even need the proc of removecolor. The above recolor procs both work fine, how ever I need to change the way to display the results.

> p1 := plot(sin, color = blue); p2 := plot(cos, color = green);
> recolor := proc (p, c) options operator, arrow; eval(p, COLOUR = proc () convert(color = c, PLOToptions)[] end proc) end proc;
> plots[display]({recolor(p2, "Yellow"), recolor(p1, "Red")});
 

Thanks Robert and Joe.

The first example works well, but the second failed. The following error message was shown:

Error, (in ColorTools:-NameToRGB) unknown color name

I wondered that the third line in the proc. where does  'cls' comes from?

I think there might be some text format issue about the editor.

I mean If I just open Maple and try above command, there is no error. It will happen after I have done some other operations. Then I save and close the worksheet. The same command will work fine if I open the same worksheet. I found that when these errors happens and you copy the command "a:=[1,2]" to a text editor, it is shown as "a:=(1,2)". If I reopen the maple file and do the same operation. I got "a:=[1,2]" again. Another observation is that if I write the command in a Text format in maple, then no error shows up.

Thanks you all so much.

I feel like the sum more, since it has a math symbol for it, which can make the worksheet more understandable.

Thank you all very much! My problem solved. I happened to named my input parameter as "procname", which turns out not to be valid name for a vairable. That's the resean why I got wrong message when I call the procedure. Thanks for your guys kindly rsponse.

Thanks. Your information is enough for me.

I just want to use both of the criteria.

Somehow, the order of the option matters:

fsolve({x-y = 1, x+y = 1}, {x = 0 .. 1},{x=1,y=1});

above code doesn't work in Maple,

even though the Help indicates that

"interval" should be put in front of "starting_values":

fsolve(equations, variables, complex, fulldigits, interval, starting_values, options)