# How to reduce expressions with complex coefficients in the form of a+0.*I

I'm trying to get an eigenvalue equation in Mathematica, and the result is an expression with coefficients of the form a + 0. I. For example,

Is there any clever way to simplify it? I mean the method in which I can take away the 0.*I in the expression.

## 1 Answer

Yes, Chop[] works nicely here.

Chop[1 + 0. I]
1.

• @yulinlinyu: However note that Chop changes every approximate value near zero to zero. Usually it is what you want, but you should be aware of it for the cases when you don't want to replace a numerical value of order $10^{-11}$ or below with zero (sometimes that's just the order of magnitude your numbers are expected to be in). In such cases, the optional second argument of Chop comes in handy. – celtschk Jun 18 '12 at 15:49
• @celt: good note. At least in OP's case, this isn't a worry, but still good to be wary when your expression has a mix of genuinely tiny constants and stuff that really ought to be zero. – J. M. will be back soon Jun 18 '12 at 15:53