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I have the following line: $0 \leqslant b \leqslant 1$

I want to display 0 <= b <= 1, but I get Undefined control sequence


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Are you loading the amssymb package? – Gonzalo Medina Apr 25 '11 at 16:42
up vote 14 down vote accepted

do you want it like this way? $0 \le b \le 1$. Otherwise load \usepackage{amssymb}

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You should use the amssymb package.

$0 \leqslant b \leqslant 1$
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