Python script to expand Fourier's series.

fourier_series_expansion.py

#! /usr/local/bin/python3.6
"""
Fourier's series expansion

  f(t) = -1 (-pi < t <= 0 )
          1 (  0 < t <= pi)
"""
import math
import sys
import traceback


class FourierSeriesExpansion:
    N = 3  # Number of items
    CSV_FILE = "FourierSeriesExpansion.csv"

    def expand_fourier_series(self):
        """ Fourier's series expansion """
        try:
            with open(self.CSV_FILE, "w") as f:
                f.write("t,f(t)\n")
                y = 0
                for t in range(int(math.pi * -1000), int(math.pi * 1000) + 1):
                    for i in range(1, self.N + 1):
                        y += self.__calc_term(i, t / 1000.0)
                    ft = 4 / math.pi * y
                    f.write("{:.3f},{:.6f}\n".format(t / 1000.0, ft))
                    y = 0
        except Exception as e:
            raise

    def __calc_term(self, n, t):
        """ Computation for each item

        :param  int n
        :param  int t
        :return float
        """
        try:
            return math.sin((2 * n - 1) * t) / (2 * n - 1)
        except Exception as e:
            raise


if __name__ == '__main__':
    try:
        obj = FourierSeriesExpansion()
        obj.expand_fourier_series()
    except Exception as e:
        traceback.print_exc()
        sys.exit(1)