- defines a C<root> function for n-th root of x.

From WeBWorK

Jump to: navigation

NAME - defines a root(n,x) function for n-th root of x.


This file defines the code necessary to add to any context a root(n,x) function that performs the n-th root of x. For example, Compute("root(3,27)") would return the equivalent of Real(3).

To accomplish this, put the line


at the beginning of your problem file, then set the Context to the one you wish to use in the problem. Then use the command:


(You can also pass the Enable command a pointer to a context if you wish to alter a context other than the current one.)

Once that is done, you (and students) can enter roots by using the root() function. You can use root() both within Formula() and Compute() calls, and in Perl expressions, such as

        $n = root(3,27);

to obtain n-th roots. Note that root() will properly handle odd roots of negative numbers, so

        $n = root(3,-8);

will produce the equivalent of $n = Real(-2), but even roots of negative numbers will produce an error message.

If you enable root() in a context that allows complex numbers, you may want to allow even roots of negative numbers. To do this, use


(again, you can pass a context to be altered, if you wish). This will force negative values to be promoted to complex numbers before an even root is taken. So

        $z = root(2,-9);

would produce the equivalent of $z = 3*i;