These commands test expr for various forms of function composition.

The type(expr, `@`) calling sequence returns true if expr is a composition of functions.  It is equivalent to type(expr, specfunc(anything, `@`)).

The type(expr, `@@`) calling sequence returns true if expr is a repeated composition.  It is equivalent to type(expr, specfunc(anything, `@@`)).

The type(expr, composition) calling sequence returns true if expr is either of type @ or @@.

For more information about function composition, see compose.

$\mathrm{type}\left(\sin @\cos \,\mathrm{`@`}\right)$

$\mathrm{true}$

$\mathrm{type}\left(\sin @\cos @\csc \,\mathrm{`@`}\right)$

$\mathrm{true}$

$\mathrm{type}\left({\csc }^{\left(2\right)}\,\mathrm{`@@`}\right)$

$\mathrm{true}$

$\mathrm{type}\left({\left(\cos @\sin \right)}^{\left(2\right)}\,\mathrm{`@@`}\right)$

$\mathrm{true}$

$\mathrm{type}\left(\sin @\cos \,\mathrm{composition}\right)$

$\mathrm{true}$

$\mathrm{type}\left({\sin }^{\left(2\right)}@{\cos }^{\left(2\right)}\,\mathrm{composition}\right)$

$\mathrm{true}$

$\mathrm{type}\left(\sin \,\mathrm{`@@`}\right)$

$\mathrm{false}$

$\mathrm{type}\left({\sin }^{\left(0\right)}\,\mathrm{`@@`}\right)$

$\mathrm{false}$

$\mathrm{type}\left(\sin \left(\cos \left(x\right)\right)\,\mathrm{composition}\right)$

$\mathrm{false}$