Computation for error analysis

error_analysis.py

# Numerical Analysis, Summer Semester A.Y. 2015-2016, Adamson University
# Author: A.F. Agarap
# Error Analysis

import os

def main():
	true_value = float(eval(input("Enter true value: ")))
	approximate_value = float(eval(input("Enter approximate value: ")))
	float_range = int(input("Enter number of precision values: "))
	chop_approximate_value = truncate(approximate_value, float_range)
	chop_error = get_error(true_value, chop_approximate_value)
	chop_relative_error = get_relative_error(true_value, chop_approximate_value)
	round_approximate_value = round_val(approximate_value, float_range)
	round_error = get_error(true_value, round_approximate_value)
	round_relative_error = get_relative_error(true_value, round_approximate_value)
	print("Chop()\n\tError: {}".format(chop_error),"\n","\b\tRelative Error: {}%".format(chop_relative_error))
	print("\nRound()\n\tError: {}".format(round_error),"\n","\b\tRelative Error: {}%".format(round_relative_error))


# Author: David Z, A.F. Agarap
# Link: http://goo.gl/DTdDEt
def truncate(f, n):
    '''Truncates/pads a float f to n decimal places without rounding'''
    s = '{}'.format(f)
    if 'e' in s or 'E' in s:
        return '{0:.{1}f}'.format(f, n)
    i, p, d = s.partition('.')
    return float('.'.join([i, (d+'0'*n)[:n]]))

def round_val(f, n):
	return float('{0:.{1}f}'.format(f, n))

def get_error(true_value, approximate_value):
	return (abs(true_value - approximate_value))

def get_relative_error(true_value, approximate_value):
	return (abs(true_value - approximate_value) / abs(true_value))

main()