SQR - QB64 Wiki

SQR

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The SQR function returns the square root of a numerical value.


Syntax:

square_root = SQR(value)


  • The square root returned is normally a SINGLE or DOUBLE numerical value.
  • The value parameter can be any positive numerical type. Negative parameter values will not work!
  • Other exponential root functions can use fractional exponents(^) enclosed in parenthesis only. EX: root = c ^ (a / b)


Example 1: Finding the hypotenuse of a right triangle:

A% = 3: B% = 4 PRINT "hypotenuse! ="; SQR((A% ^ 2) + (B% ^ 2))

hypotenuse = 5


Example 2: Finding the Cube root of a number.

number = 8 cuberoot = number ^ (1/3) PRINT cuberoot

2


Example 3: Negative roots return fractional values of one.

number = 8 negroot = number ^ -2 PRINT negroot

.015625

Explanation: A negative root means that the exponent value is actually inverted to a fraction of 1. So x ^ -2 actually means the result will be: 1 / (x ^ 2).


Example 4: Fast Prime number checker limits the numbers checked to the square root (half way).

DEFLNG P DO PRIME = -1 'set PRIME as True INPUT "Enter any number to check up to 2 million (Enter quits): ", guess$ PR = VAL(guess$) IF PR MOD 2 THEN 'check for even number FOR P = 3 TO SQR(PR) STEP 2 'largest number that could be a multiple is the SQR IF PR MOD P = 0 THEN PRIME = 0: EXIT FOR 'MOD = 0 when evenly divisible by another NEXT ELSE : PRIME = 0 'number to be checked is even so it cannot be a prime END IF IF PR = 2 THEN PRIME = -1 '2 is the ONLY even prime IF PR = 1 THEN PRIME = 0 'MOD returns true but 1 is not a prime by definition IF PRIME THEN PRINT "PRIME! How'd you find me? " ELSE PRINT "Not a prime, you lose!" LOOP UNTIL PR = 0

Enter any number to check up to 2 million (Enter quits): 12379 PRIME! How'd you find me?

Note: Prime numbers cannot be evenly divided by any other number except one.


See also:



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