qb64/internal/help/SQR.txt

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


{{PageSyntax}}
:square_root = [[SQR]](value)


{{PageDescription}}
* 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: {{text|root <nowiki> = </nowiki> c ^ (a / b)|green}}


{{PageExamples}}
''Example 1:'' Finding the hypotenuse of a right triangle:
{{CodeStart}} '' ''
 A% = 3: B% = 4
 {{Cl|PRINT}} "hypotenuse! ="; {{Cl|SQR}}((A% ^ 2) + (B% ^ 2)) '' ''
{{CodeEnd}}
{{OutputStart}}
 hypotenuse = 5
{{OutputEnd}}


''Example 2:'' Finding the Cube root of a number. 
{{CodeStart}} '' ''
 number = 8
 cuberoot = number {{Cl|^}} (1/3)
 {{Cl|PRINT}} cuberoot '' ''
{{CodeEnd}}
{{OutputStart}}
 2
{{OutputEnd}}


''Example 3:'' Negative roots return fractional values of one.
{{CodeStart}} '' ''
 number = 8
 negroot = number {{Cl|^}} -2
 {{Cl|PRINT}} negroot '' ''
{{CodeEnd}}
{{OutputStart}}
 .015625
{{OutputEnd}}
:''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).
{{CodeStart}}
{{Cl|DEFLNG}} P
{{Cl|DO}}
PRIME = -1   'set PRIME as True
{{Cl|INPUT}} "Enter any number to check up to 2 million (Enter quits): ", guess$
PR = {{Cl|VAL}}(guess$)
{{Cl|IF}} PR {{Cl|MOD}} 2 {{Cl|THEN}}              'check for even number
  {{Cl|FOR}} P = 3 {{Cl|TO}} {{Cl|SQR}}(PR) {{Cl|STEP}} 2 'largest number that could be a multiple is the SQR
    {{Cl|IF}} PR {{Cl|MOD}} P = 0 {{Cl|THEN}} PRIME = 0: {{Cl|EXIT FOR}} 'MOD = 0 when evenly divisible by another
  {{Cl|NEXT}}
{{Cl|ELSE}} : PRIME = 0 'number to be checked is even so it cannot be a prime
{{Cl|END IF}}
{{Cl|IF}} PR = 2 {{Cl|THEN}} PRIME = -1 '2 is the ONLY even prime
{{Cl|IF}} PR = 1 {{Cl|THEN}} PRIME = 0  'MOD returns true but 1 is not a prime by definition
{{Cl|IF}} PRIME {{Cl|THEN}} {{Cl|PRINT}} "PRIME! How'd you find me? " {{Cl|ELSE}} {{Cl|PRINT}} "Not a prime, you lose!"
{{Cl|LOOP}} {{Cl|UNTIL}} PR = 0 '' ''
{{CodeEnd}}
{{OutputStart}}
Enter any number to check up to 2 million (Enter quits): 12379
PRIME! How'd you find me?
{{OutputEnd}}
<center>''Note:'' Prime numbers cannot be evenly divided by any other number except one.</center>


{{PageSeeAlso}}
*[[MOD]] {{text|(integer remainder division)}}
*[[^]] {{text|(exponential operator)}}
*[[Mathematical Operations]]
*[[Mathematical_Operations#Derived_Mathematical_Functions|Derived Trigonometric Functions]]


{{PageNavigation}}