This is a utility function for use in conjunction with nag_fft_multiple_real (c06fpc) and nag_fft_multiple_hermitian (c06fqc). nag_fft_init_trig (c06gzc) initializes the array trig with trigonometric coefficients according to the value of n and must be called prior to the first call of one of the above listed functions.

4 References

None.

5 Arguments

1: $n$ – IntegerInput: On entry: the value of $n$ in the Fourier transform function being called.

Constraint: $n \geq 1$ .
2: $trig [2 \times n]$ – doubleOutput: On exit: the trigonometric coefficients are stored in trig.
3: $fail$ – NagError *Input/Output: The NAG error argument (see Section 2.7 in How to Use the NAG Library and its Documentation).

6 Error Indicators and Warnings

NE_INT_ARG_LT: On entry, $n = 〈value〉$ .
Constraint: $n \geq 1$ .

7 Accuracy

Exact.

8 Parallelism and Performance

nag_fft_init_trig (c06gzc) is not threaded in any implementation.

9 Further Comments

None.

10 Example

The program reads in 3 real data sequences and prints their discrete Fourier transforms in Hermitian format as calculated by nag_fft_multiple_real (c06fpc). A call is made to nag_fft_init_trig (c06gzc) to initialize the array trig prior to calling nag_fft_multiple_real (c06fpc). The transforms are then printed out in full complex form after a call to nag_multiple_hermitian_to_complex (c06gsc).

NAG Library Function Documentnag_fft_init_trig (c06gzc)

▸▿ Contents

1 Purpose

2 Specification

3 Description

4 References

5 Arguments

6 Error Indicators and Warnings

7 Accuracy

8 Parallelism and Performance

9 Further Comments

10 Example

10.1 Program Text

10.2 Program Data

10.3 Program Results

NAG Library Function Document

nag_fft_init_trig (c06gzc)