FAIL
-- indicate a failed
computationFAIL
is a keyword of the MuPAD language. Many
functions of the library use the return value FAIL
to
indicate failed computations or non-existing elements.
FAIL
FAIL
is the only element of the domain DOM_FAIL
.FAIL
is used as the return value for computations that
failed. Also, requesting non-existing slots of
domains or function
environments yields FAIL
. Due to this behavior,
library functions can try computations without provoking errors.FAIL
or an error if at least
one of its inputs is FAIL
.The following attempt to convert sqrt(3)
to
an integer of a residue class ring must fail:
>> poly(sqrt(3)*x, [x], Dom::IntegerMod(3))
FAIL
The following matrix is not invertible. You can try to invert it without producing an error:
>> A := matrix([[1, 1], [1, 1]]): 1/A
FAIL
The "inverse"
slot of a function
environment yields the inverse of the function. The inverse of the sine function is implemented, but MuPAD
does not know the inverse of the dilogarithm
function:
>> sin::inverse, dilog::inverse
"arcsin", FAIL
>> delete A:
Most functions return FAIL
or an error on
input of FAIL
:
>> poly(FAIL)
FAIL
>> sin(FAIL)
Error: argument must be of 'Type::Arithmetical' [sin]
FAIL
evaluates to itself:
>> FAIL, eval(FAIL), level(FAIL, 5)
FAIL, FAIL, FAIL