FAIL

Indicate a failed computation

Use only in the MuPAD Notebook Interface.

This functionality does not run in MATLAB.

Syntax

FAIL

Description

FAIL 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 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.

A function should return FAIL or an error if at least one of its inputs is FAIL.

Examples

Example 1

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))

The following matrix is not invertible. You can try to invert it without producing an error:

A := matrix([[1, 1], [1, 1]]): 1/A

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

delete A:

Example 2

Most functions return FAIL or an error on input of FAIL:

poly(FAIL)

sin(FAIL)
Error: An arithmetical expression is expected. [sin]

Example 3

FAIL evaluates to itself:

FAIL, eval(FAIL), level(FAIL, 5)

See Also

MuPAD Functions

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