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Type::Predicate

Type for testing object satisfying a given predicate

Use only in the MuPAD Notebook Interface.

This functionality does not run in MATLAB.

Syntax

testtype(obj, Type::Predicate(<pname>, predicate, <p1, p2, …>))

Description

Type::Predicate(predicate) represents the MuPAD® objects which satisfy the predicate predicate.

The call testtype(obj, pname, Type::Predicate(< pname >, predicate , < p1 , p2 >)) test whether obj satisfies predicate; that is it returns predicate(obj, p1, p2, ...).

Type::Predicate(predicate), Type::Predicate(name, predicate), Type::Predicate ( predicate( p1 , p2 , …)), and Type::Predicate(name, predicate p1 , p2 , , …) are respectively pretty printed as Type::Predicate(predicate), Type::name, Type::Predicate(p, p1, p2, ...), and Type::name(p1, p2, ...).

Examples

Example 1

We define a type which contains any MuPAD object:

t := Type::Predicate(x -> TRUE):
testtype(1, t), testtype(2, t), testtype(x, t)

We define a type which contains all the MuPAD object which are solution of (x-1)*(x+1)=0:

t := Type::Predicate(x -> bool((x - 1)*(x + 1) = 0)):
testtype(1, t), testtype(2, t), testtype(x, t)

We define a type for partitions, that is, decreasing lists of integers:

part :=
    Type::Predicate(l -> _lazy_and(testtype(l, Type::ListOf(Type::Integer)),
                                   bool(revert(sort(l)) = l))):
testtype(a, part), testtype([3, 6, 1], part), testtype([3, 2, 2], part)

Using the naming facility is recommended to improve the readability of error messages:

part :=
    Type::Predicate("Partition",
                    l -> _lazy_and(testtype(l, Type::ListOf(Type::Integer)),
                                   bool(revert(sort(l)) = l))):
f := proc(p: part) begin end:
f(3);
Error: The type of argument number 1 must be 'Type::Partition'. The object '3' is incorrect.
  Evaluating: f

Parameters

pname

A string which will be used for pretty printing the type

predicate

A function of one argument which can return TRUE, FALSE or FAIL

obj, p1, p2, …

Any MuPAD objects

Return Values

See testtype

See Also

MuPAD Functions

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