Source code for pymeeus.base

# -*- coding: utf-8 -*-

# PyMeeus: Python module implementing astronomical algorithms.
# Copyright (C) 2018  Dagoberto Salazar
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# GNU Lesser General Public License for more details.
# You should have received a copy of the GNU Lesser General Public License
# along with this program.  If not, see <>.

from math import floor

.. module:: base
   :synopsis: Basic routines and constants used by the pymeeus module
   :license: GNU Lesser General Public License v3 (LGPLv3)

.. moduleauthor:: Dagoberto Salazar

TOL = 1e-10
"""Internal tolerance being used by default"""

[docs]def machine_accuracy(): """This function computes the accuracy of the computer being used. This function returns a tuple containing the number of significant bits in the mantissa of a floating number, and the number of significant digits in a decimal number. :returns: Number of significant bits, and of significant digits :rtype: tuple """ j = 0.0 x = 2.0 while x + 1.0 != x: j += 1.0 x *= 2.0 return (j, int(j * 0.30103))
[docs]def get_ordinal_suffix(ordinal): """Method to get the suffix of a given ordinal number, like 1'st', 2'nd', 15'th', etc. :param ordinal: Ordinal number :type ordinal: int :returns: Suffix corresponding to input ordinal number :rtype: str :raises: TypeError if input type is invalid. >>> get_ordinal_suffix(40) 'th' >>> get_ordinal_suffix(101) 'st' >>> get_ordinal_suffix(2) 'nd' >>> get_ordinal_suffix(19) 'th' >>> get_ordinal_suffix(23) 'rd' """ if not isinstance(ordinal, (int, float)): raise TypeError("Invalid input type") else: ordinal = int(floor(ordinal)) unit = ordinal % 10 if unit == 1 and ordinal != 11: return "st" elif unit == 2 and ordinal != 12: return "nd" elif unit == 3 and ordinal != 13: return "rd" else: return "th"
[docs]def iint(number): """This method behaves in the same way as the **INT()** function described by Meeus in his book: Greatest integer which is not greater than number. :param number: Number or expresion :type number: int, float :returns: Greatest integer which is not greater than number :rtype: int :raises: TypeError if input type is invalid. >>> iint(19) 19 >>> iint(19.95) 19 >>> iint(-2.4) -3 """ if not isinstance(number, (int, float)): raise TypeError("Invalid input type") else: return int(floor(number))
def main(): # Let's define a small helper function def print_me(msg, val): print("{}: {}".format(msg, val)) # Let's print the tolerance print_me("The default value for the tolerance is", TOL) # Find the accuracy of this computer j, d = machine_accuracy() print_me("Number of significant BITS in the mantissa\t", j) print_me("Number of significant DIGITS in a decimal number", d) print("") print_me("The suffix for ordinal 2 is", get_ordinal_suffix(2)) print_me("The suffix for ordinal 11 is", get_ordinal_suffix(11)) print_me("The suffix for ordinal 12 is", get_ordinal_suffix(12)) print_me("The suffix for ordinal 13 is", get_ordinal_suffix(13)) print_me("The suffix for ordinal 14 is", get_ordinal_suffix(14)) print_me("The suffix for ordinal 16 is", get_ordinal_suffix(16)) print_me("The suffix for ordinal 23 is", get_ordinal_suffix(23)) if __name__ == "__main__": main()