Routine Name: dmaceps
Author: Brandon Furman
Language: C++
Description/Purpose: This routine will compute the double precision value for the machine epsilon or the number of digits in the representation of real numbers in single precision. This is a routine for analyzing the behavior of any computer. This usually will need to be run one time for each computer.
Input: There are no inputs needed for this routine.
Output: This routine returns a double precision value for the number of decimal digits that can be represented on the computer being queried.
Usage/Example: The routine has no arguments and only outputs the default machine precision in terms of a decimal number. For example, the following code:
std::cout << dmaceps();
outputs the following to the console:
1.11022e-16
Implementation/Code: The following is the code for dmaceps()
double dmaceps() {
//Set up storage for the algorithm and initialize
//variables to compute the machine value near 1.0
double one = 1.0;
double seps = 1.0;
double appone = one + seps;
//Loop, dividing by 2 each time to determine when the difference
//between one and the approximation is zero in single precision
while (abs(appone - one) != 0.0) {
seps = seps / 2.0;
appone = one + seps;
}
return seps;
}
Last Modified: January/2019