1.8 Numerical Determination of Fourier Coefficients

1.8 Numerical Determination of Fourier Coefficients

  • Most of the series disappears.
  • The sum term by term is what Lemma 1 needs to be verified.

  • The integrals involved in many functions are not known in terms of easily evaluated functions.
    • It is possible that a function can be found at some point.
    • If a Fourier series is to be found for the function, some numerical technique must be used to approximate the integrals that give the coefficients.
    • One of the crudest numerical integration techniques is the best.

  • We want to find its coefficients numerically.
  • The trapezoidal rule is used to approximate the integral.

  • The two terms can be combined.

  • The usual coefficients name is used to designate approximations.
  • The other coefficients are approximated in the same way.

  • Calculating efficients can be done.

  • Table 3 has the numerical information.
  • Table 4 contains the results of the calculation.
    • The approx imate coefficients are on the left.
  • This is not a consideration when the calculation is done with a digital computer.

  • The first month of the year represents the depth of the water in Lake Ontario.
    • The mean level and fluctuations of period 12 months, 6 months, 4 months, and so forth are identified.
  • The table shows the monthly precipi tation in Lake Placid, NY, from 1950 to 1959.