Auxiliary Functions in PG

The macro file PGauxiliaryFunctions.pl, which is automatically loaded by PGstandard.pl, contains many useful numerical recipies.

1. The max function max(-1,4,2*pi,5); will return 6.28319.
   
   
2. The min function min(10,2*pi,-1,5); will return -1.
   
   
3. The greatest common factor (or divisor) function gcf(4,6); or gcd(4,6); will return 2. For perl code that gives an extended gcd function xgcd(a,b) = d = ax+by, see the online references below.
   
   
4. The least common multiple function lcm(4,6); will return 12.
   
   
5. The ceiling and floor functions ceil(-3.4); and floor(-3.4); will return -3 and -4.
   
   
6. The prime test function isPrime(4); and isPrime(5); will return 0 and 1.
   
   
7. The signum (or sign) function sgn(-pi); and sgn(0); and sgn(6) will return -1, 0, and 1.
   
   
8. The Heaviside step function, which is 1 when the input is positive and zero otherwise, is step(-0.1); and step(0); and step(0.1); which returns 0, 0, and 1.
   
   
9. The integer rounding function round(1.49999); and round(1.5); and round(-1.5); and round(-1.49999); will return 1, 2, -2, -1.

Online References

• Standard PG macros (POD documentation)
• Standard PG macros (source)
• Extendend gcd function