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iscoprime

Check coprime relation

Description

example

iscp = iscoprime(x) returns true if all elements of x are coprime and false if two or more elements of x have a greatest common divisor (gcd) greater than 1.

[iscp,ispcp,pidx,pgcd] = iscoprime(x) checks if pairs of elements of x have a greatest common divisor greater than 1. This syntax also returns the indices of all pairs of elements of x and the greatest common divisor of each pair.

Examples

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Create an array x whose elements are 9=3×3, 15=3×5, and 25=5×5. Verify that all elements of x are coprime.

x = [9 15 25];

iscp = iscoprime(x)
iscp = logical
   1

Verify that at least one pair of elements of x has a greatest common divisor greater than 1. Output the pairs and their greatest common divisors.

[~,ispcp,pidx,pgcd] = iscoprime(x)
ispcp = logical
   0

pidx = 2×3

     1     1     2
     2     3     3

pgcd = 1×3

     3     1     5

Input Arguments

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Input array, specified as a row vector of positive integers.

Example: [21 36 49]

Data Types: single | double

Output Arguments

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True if all elements are coprime, returned as a logical scalar.

True if all elements are pairwise coprime, returned as a logical scalar. ispcp is true if x has no two elements whose greatest common divisor is greater than 1. ispcp is false if any two elements of x have as greatest common divisor a number greater than 1.

Array pair indices, returned as a two-row matrix. pidx has (n2)=12n(n1) columns. Each column of pidx specifies the indices of a pair of elements in x.

Pair greatest common divisors, returned as a row vector with a number of elements equal to the number of columns of pidx. Each element of pgcd is the greatest common divisor of the two elements of x identified by the indices in the corresponding column of pidx.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

See Also

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Introduced in R2021a