IsFalse returns true if expr is identically false, or a list whose first element is false, and returns false otherwise.

IsFail returns true if expr is identically FAIL, or a list whose first element is FAIL, and returns false otherwise.

IsFalse(expr) is equivalent to type(expr, verify(false)) except that it should be faster; similarly IsFail(expr) is equivalent to type(expr, verify(FAIL)) except faster.

$\mathrm{with}\left(\mathrm{VerifyTools}\right)\:$

$\mathrm{IsFalse}\left(\mathrm{false}\right)$

$\mathrm{true}$

$\mathrm{expr}≔\mathrm{verify}\left(3.14\,\mathrm{evalf}\left(\mathrm{\pi }\right)\,\mathrm{float}\left(10\right)\right)$

$\mathrm{expr}≔\left[\mathrm{false}\,1.59\times {10}^6\,\mathrm{ulps}\right]$

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

$\mathrm{true}$

$\mathrm{Digits}≔4\:$

$\mathrm{IsFalse}\left(\mathrm{verify}\left(3.14\,\mathrm{evalf}\left(\mathrm{\pi }\right)\,\mathrm{float}\left(10\right)\right)\right)$

$\mathrm{false}$

$\mathrm{IsFail}\left(\mathrm{FAIL}\right)$

$\mathrm{true}$

$\mathrm{IsFail}\left(\mathrm{true}\right)$

$\mathrm{false}$

$\mathrm{IsFail}\left(\mathrm{false}\right)$

$\mathrm{false}$