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Real function for symbolic variables

Asked by David Koenig on 16 Oct 2011
why does
>>real(2+3*i)
give me an error message while
>> imag(2+3*i)
ans =
3
works?

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3 Answers

Answer by the cyclist
on 16 Oct 2011

What error message do you get? Neither of those commands gives an error for me. Might you have redefined the real() command somehow? Does
>> which real
give the expected file location? (It should be a built-in function in the elfun directory structure.)

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Answer by Walter Roberson
on 16 Oct 2011

2+3*i would not inherently involve the symbolic toolbox, not unless you have overwritten "i" with a symbolic variable.
Is the 2+3*i perhaps a value that you had returned from a symbolic calculation without using double(), and is thus sym('2+3*i') ?

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Answer by David Koenig on 17 Oct 2011

Thanks for the responses, the cyclist and Walter Roberson. I think my problem had to do with not declaring the variables properly in a syms statement. I have since been more careful and have resolved the issues - and using 2011a instead of 6.1 has made a pleasant difference.

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