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Arithmetic method and function arithmetic circuit for a fast fourier transform

  • US 7,634,524 B2
  • Filed: 04/14/2004
  • Issued: 12/15/2009
  • Est. Priority Date: 12/12/2003
  • Status: Expired due to Fees
First Claim
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1. A function arithmetic method comprising:

  • a cyclic equation setting step performed by an arithmetic unit of a circuit for transforming and setting a Taylor series equation for calculating a sine function into a single cyclic equation common to terms of the Taylor series equation, the single cyclic equation having a new known number Q that is defined by multiplying a known number Q and the square of a variable X, shifting the result by a shift number S and then adding a constant K thereto;

    an adjustment step performed by an adjustment unit of said circuit for adjusting and preparing the shift number S such that within a variation range of the variable X the variable X has a maximum value 1 with the constant K being not greater than 1;

    a cyclic equation executing step preformed by the adjustment unit of said circuit for inputting and converting angle information i to the variable X, and executing the cyclic equation in sequence from higher order term to lower order term for the number of terms of the Taylor series equation to derive a sine function of the angle information i; and

    an output step outputting the sine function for a fast Fourier transform.

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