# SQR

### From QB64 Wiki

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

- square_root =
**SQR(**value**)**

- square_root =

- 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:*

- MOD (integer remainder division)
- ^ (exponential operator)
- Mathematical Operations
- Derived Trigonometric Functions

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