NAG Library Manual, Mark 27.2
Interfaces:  FL   CL   CPP   AD 
NAG CL Interface Introduction
C06 (Sum) Chapter Contents
C06 (Sum) Chapter Introduction
c06gz:  FL   CL   CPP   AD 

NAG CL Interface
c06gzc (init_​trig)

Note: this function is deprecated and will be withdrawn at Mark 29. There is no replacement for this function.
NAG Library Manual, Mark 27.2
Interfaces:  FL   CL   CPP   AD 
NAG CL Interface Introduction
C06 (Sum) Chapter Contents
C06 (Sum) Chapter Introduction
c06gz:  FL   CL   CPP   AD 

▸▿ Contents

© The Numerical Algorithms Group Ltd. 2021
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1 Purpose

c06gzc calculates the trigonometric coefficients required for the computation of discrete Fourier transforms.

2 Specification

#include <nag.h>
void  c06gzc (Integer n, double trig[], NagError *fail)
The function may be called by the names: c06gzc, nag_sum_init_trig or nag_fft_init_trig.

3 Description

This is a utility function for use in conjunction with c06fpc and c06fqc. 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 – Integer Input
On entry: the value of n in the Fourier transform function being called.
Constraint: n≥1 .
2: trig[2×n] – double Output
On exit: the trigonometric coefficients are stored in trig.
3: fail – NagError * Input/Output
The NAG error argument (see Section 7 in the Introduction to the NAG Library CL Interface).

6 Error Indicators and Warnings

NE_INT_ARG_LT
On entry, n=⟨value⟩.
Constraint: n≥1.

7 Accuracy

Exact.

8 Parallelism and Performance

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 c06fpc. A call is made to c06gzc to initialize the array trig prior to calling c06fpc. The transforms are then printed out in full complex form after a call to c06gsc.

10.1 Program Text

Program Text (c06gzce.c)

10.2 Program Data

Program Data (c06gzce.d)

10.3 Program Results

Program Results (c06gzce.r)
NAG Library Manual, Mark 27.2
Interfaces:  FL   CL   CPP   AD 
NAG CL Interface Introduction
C06 (Sum) Chapter Contents
C06 (Sum) Chapter Introduction
c06gz:  FL   CL   CPP   AD 
© The Numerical Algorithms Group Ltd. 2021