/, _divide

Divide expressions

Use only in the MuPAD Notebook Interface.

This functionality does not run in MATLAB.

Syntax

x / y
_divide(x, y)

Description

x/y computes the quotient of x and y.

x/y is equivalent to the function call _divide(x, y).

For numbers of type Type::Numeric, the quotient is returned as a number.

If neither x nor y are elements of library domains with "_divide" methods, x/y is internally represented as x * y^(-1) = _mult(x, _power(y, -1)).

If x or y is an element of a domain with a slot"_divide", then this method is used to compute x/y. Many library domains overload the / operator by an appropriate "_divide" slot. Quotients are processed as follows:

x/y is searched for elements of library domains from left to right. Let z (either x or y) be the first term that is not of one of the basic types provided by the kernel (numbers, expressions, etc.). If the domain d = z::dom = domtype(z) has a slot"_divide", it is called in the form d::_divide(x, y). The result returned by d::_divide is the result of x/y.

Cf. examples Example 4 and Example 5.

Polynomials of type DOM_POLY can be divided by /, if they have the same indeterminates and the same coefficient ring, and if exact division is possible. The function divide can be used to compute the quotient of polynomials with a remainder term.

For finite sets X, Y, the quotient X/Y is the set .

Examples

Example 1

The quotient of numbers is simplified to a number:

1234/234, 7.5/7, 6*I/2

Internally, a symbolic quotient x/y is represented as the product x * y^(-1):

type(x/y), op(x/y, 0), op(x/y, 1), op(x/y, 2)

op(op(x/y, 2), 0), op(op(x/y, 2), 1), op(op(x/y, 2), 2)

Example 2

For finite sets X, Y, the quotient X/Y is the set :

{a, b, c} / {2, 3}

Example 3

Polynomials of type DOM_POLY can be divided by / if they have the same indeterminates, the same coefficient ring, and if exact division is possible:

poly(x^2 - 1, [x]) / poly(x - 1, [x])

poly(x^2 - 1, [x]) / poly(x - 2, [x])

The function divide provides division with a remainder:

divide(poly(x^2 - 1, [x]), poly(x - 2, [x]))

The polynomials must have the same indeterminates and the same coefficient ring:

poly(x^2 - 1, [x, y]) / poly(x - 1, [x])
Error: The argument is invalid. [divide]

Example 4

Various library domains such as matrix domains overload _divide. The matrix domain defines x/y as x * (1/y), where 1/y is the inverse of y:

x := Dom::Matrix(Dom::Integer)([[1, 2], [3, 4]]):
y := Dom::Matrix(Dom::Rational)([[10, 11], [12, 13]]):
x/y

The inverse of x has rational entries. Therefore, 1/x returns FAIL, because the component ring of x is Dom::Integer. Consequently, also y/x returns FAIL:

y/x

delete x, y:

Example 5

This example demonstrates the behavior of _divide on user-defined domains. In the first case below, the user-defined domain does not have a "_divide"slot. Thus x/y is transformed to x * (1/y):

Do := newDomain("Do"): x := new(Do, 1): y := new(Do, 2):
x/y; op(x/y, 0..2)

After the slot"_divide" is defined in the domain Do, this method is used to divide elements:

Do::_divide := proc() begin "The Result" end: x/y

delete Do, x, y:

Parameters

x, y, …

arithmetical expressions, polynomials of type DOM_POLY, or sets

Return Values

Arithmetical expression, a polynomial, or a set.

Overloaded By

x, y

See Also

MuPAD Functions

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