The sign function computes the sign of the leading coefficient of expr. The sign function works for polynomials with coefficients of type `numeric`. It does not take assumptions into account.

The leading coefficient of expr is determined with respect to the indeterminates given.  If none are given, the leading coefficient is taken with respect to all its indeterminates.  Note therefore that the leading coefficient is dependent on the order of the indeterminates which may vary from one Maple session to another, but not within a session.

The unevaluated name specified as the optional third argument is assigned the leading term.

The sign command is thread-safe as of Maple 15 .

For more information on thread safety, see index/threadsafe.

$\mathrm{sign}\left(0\right)$

$1$

$\mathrm{sign}\left(-\frac{2}{3}\right)$

$\mathrm{-1}$

$\mathrm{expr}≔3x^2{y}^4-2x{y}^5+x$

$\mathrm{expr}≔3x^2{y}^4-2x{y}^5+x$

$\mathrm{indets}\left(\mathrm{expr}\right)$

$\left\{x\,y\right\}$

$\mathrm{sign}\left(\mathrm{expr}\right)$

$1$

$\mathrm{sign}\left(\mathrm{expr}\,\left[x\,y\right]\right)$

$1$

$\mathrm{sign}\left(\mathrm{expr}\,\left[y\,x\right]\right)$

$\mathrm{-1}$

$\mathrm{sign}\left(\mathrm{expr}\,\left[y\,x\right]\,'a'\right)$

$\mathrm{-1}$

$a$

$x{y}^5$

$\mathrm{plot}\left(\mathrm{sign}\left(x\right)\,x=-1..1\right)$

$\mathrm{plot}\left('\mathrm{sign}\left(x\right)'\,x=-1..1\right)$