#### Description:

This subroutine modifies the supplied array of Fourier
coefficients (as produced by NAG subroutine C06FAF) so that an inverse FFT can be performed on
them using FFTPACK routine PDA_RFFTB. The resulting inverse will have the same normalisation as
the original data transformed using PDA_RFFTF.

#### Invocation

CALL PDA_NAG2R( NP, R )

#### Arguments

##### NP = INTEGER (Given)

The size of the array.

##### R( NP ) = REAL (Given and Returned)

The array holding the Fourier coefficients. Supplied in NAG format and returned in FFTPACK format.

#### Implementation Status:

A double precision version PDA_DNAG2R of the routine exists.

#### Notes:

A
call to PDA_R2NAG followed by a call to PDA_NAG2R will result in the original data being divided
by NP.

Some speed is sacrificed in order to perform the conversion in-situ.