R: isprime Property

isprime {pracma} | R Documentation

## isprime Property

### Description

Vectorized version, returning for a vector or matrix of positive integers a vector of the same size containing 1 for the elements that are prime and 0 otherwise.

### Usage

      isprime(x)

### Arguments

`x` | vector or matrix of nonnegative integers

### Details

Given an array of positive integers returns an array of the same size of 0 and 1, where the i indicates a prime number in the same position.

### Value

array of elements 0, 1 with 1 indicating prime numbers

### See Also

`factors, primes`

### Examples

      x <- matrix(1:10, nrow=10, ncol=10, byrow=TRUE)
      x * isprime(x)

      # Find first prime number octett:
      octett <- c(0, 2, 6, 8, 30, 32, 36, 38) - 19
      while (TRUE) {
          octett <- octett + 210
          if (all(as.logical(isprime(octett)))) {
              cat(octett, "\n", sep="  ")
              break
          }
      }

[Package pracma version 2.0.4 Index]