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Sign function
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<p>In <a href="/facts/Mathematics/pxTouaz4">mathematics</a>, the sign function or signum function is a <a href="/facts/Function_(mathematics)/CdReEKCh">function</a> that has the value −1, +1 or 0 according to whether the <a href="/facts/Sign_(mathematics)/z0xollg1">sign</a> of a given <a href="/facts/Real_number/R02gw5Pb">real number</a> is positive or negative, or the given number is itself zero. In <a href="/facts/Mathematical_notation/vHgEE8cE">mathematical notation</a> the sign function is often represented as sgn x {\displaystyle \operatorname {sgn} x} or sgn ( x ) {\displaystyle \operatorname {sgn}(x)} . </p>