[Overview][Constants][Types][Classes][Procedures and functions][Index] | Reference for unit 'math' (#rtl)

# log2

Return 2-based logarithm

## Declaration

Source position: math.pp line 312

`function log2(`
`x: float`
`):float;`

## Description

Log2 returns the 2-base logarithm of X.

## Errors

If x is less than or equal to 0 an 'invalid fpu operation' error will occur.

## See also

ldexp |  | Return (2 to the power p) times x
lnxp1 |  | Return natural logarithm of 1+X
log10 |  | Return 10-Based logarithm.
logn |  | Return N-based logarithm.

## Example

    Program Example22;

    { Program to demonstrate the log2 function. }

    Uses math;

    begin
      Writeln(Log2(2):8:4);
      Writeln(Log2(4):8:4);
      Writeln(Log2(8):8:4);
      Writeln(Log2(1):8:4);
      Writeln(Log2(0.5):8:4);
      Writeln(Log2(0.25):8:4);
      Writeln(Log2(0.125):8:4);
    end.

Documentation generated on: Feb 26 2014