frexp (Function)

This function will break the value into its binary significand and an integral exponent for 2.

The values will follow the following formula:

V = significant * 2^exp

Note: This function works with DOUBLE, but can also work with FLOAT as described in the Floating-point math introductory section.

Input:

V : DOUBLE

Value to decompose.

Output:

exp : DOUBLE

Exponent

Returns: DOUBLE

The binary significant of v.

Declaration:

FUNCTION frexp : DOUBLE;
VAR_INPUT
v   : DOUBLE;
exp : ACCESS DOUBLE;
END_VAR;

Example:

INCLUDE rtcu.inc
INCLUDE math.inc
 
PROGRAM test;
VAR
  a : DOUBLE;
  b : DOUBLE;
END_VAR;
 
a := frexp(v:= 1024.0, exp := b);
DebugMsg( message := " 1024 = " + doubleToStr(v := a) + " * 2 ^ " + doubleToStr(v := b));
DebugMsg( message := " 0.5 * 2 ^ 11 = " + doubleToStr(v := ldexp(a := a, b := b)));
 
 
END_PROGRAM;