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In this Section: A list of common Maple errors and suggestion for how to solve them.

Common Maple errors

Maple will tell you when it has a problem with what you’ve asked it to do. The good news is: YOU HAVEN’T BROKEN ANYTHING! Just put your cursor back on the problem line and edit it so that it works. Here are some common Maple errors; click on an error to get suggestion for how to fix it:

Maple repeats your most recent command back to you

Maple doesn’t recognize what you typed as a command. Make sure you’ve spelled the command correctly (capital/lower case letters count!)

If you’ve spelled it right, is the command you’ve typed in a package? (see Opening Maple Packages, above).

Then, opening the appropriate package should fix the problem.

If neither spelling nor finding the command in a package works, are you using a command that was defined earlier in the worksheet? Try Execute All (the three blue exclamation points at the top middle of the screen) and see if it works.

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Warning, premature end of input

In older versions of Maple (and in Classic Worksheet Maple), Maple expects every line to end with a colon or semicolon. Go back to the command line and add a “;” at the end.

NOTE: Maple 10 has two different modes: text mode and math mode. By default, you are working in math mode. Text mode makes Maple behave like older versions of Maple. To switch between the two modes, click on the word "Text" or the word "Math" in the upper left corner of the Maple 10 window.
If you type to Maple 10 in “math mode”, you get “Warning, inserted missing semicolon at end of statement” instead of the warning above, and Maple 10 computes the expression anyway.

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Error, unable to parse
Error, invalid sequence

This usually happens when you forgot to type a number. In the examples above, I told Maple “(2 times)+4” and “2 times”. In both examples, Maple does not know what to multiply by 2.

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Maple returns an expression with letters in it when you expected a number.

Make sure that the letter that shows up was really defined earlier in the worksheet. In the example above, a has been assigned the value 42, but b has no value. When we do computations with a we get numbers, as expected. When we do computations with b, we get expressions involving b.

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Maple returns an expression with numbers when you expected letters.

Even if you delete a command from the screen, Maple still stores it in memory.

On the first line, even though I typed “a*b+c*d”, Maple remembers that earlier in my session I assigned “a:=42”.

To clear out all variables at once, use the restart; command, and Maple will behave as though you just opened a new session.

To clear out just one variable, try >unassign(‘a’);

Make sure you just used the single quote that’s on the same key as “ (not the one that’s to the left of the number 1). If you just want to reset one variable instead of losing all the information in your worksheet, “unassign” is probably the safer option.

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When I opened my saved Maple worksheet it had a nice graph like this:

But when I went back and edited the graph command, I didn’t get a picture:

This happens when you don’t execute all commands when opening a saved worksheet. Notice that if you click on execute all (those three blue exclamation points at the top of the screen), the edited graph is there!

In this example, when you opened the saved worksheet, Maple showed you what you did, but the plots package and the line that defines A:=x^2+y^2=z^2; are not in Maple’s memory until you execute them. When you told it to plot A on a new region, it didn’t recognize the plot command, or what A was, so it repeated your instructions back to you. When you “execute all”, Maple “remembers” all the earlier work you had done.

ALWAYS “execute all” when opening a saved worksheet.

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Error, (in function_name)

Maple expects different syntax for the function it’s complaining about. In the example above, Maple expects implicitplot3d to get 4 pieces of input: what to graph, bounds on x, bounds on y, bounds on z. Since I only gave it one piece of input, it’s telling me it needs more/better information before it can do what I told it to.

If you are unsure about the syntax for a command you want to use, try

> help(command_name);

The Maple help window that will pop up gives the syntax and usually several examples at the bottom to help you figure out what it expects. Try help(implicitplot3d); for an example.

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Maintained by Last modified 9/5/2006. Address questions to the Undergraduate Office of the Department of Mathematics.