Re: [eigen] Eigen/FFT |

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*To*: eigen@xxxxxxxxxxxxxxxxxxx*Subject*: Re: [eigen] Eigen/FFT*From*: Mark Borgerding <mark@xxxxxxxxxxxxxx>*Date*: Tue, 23 Jun 2009 08:41:02 -0400

Gael Guennebaud wrote:

On Tue, Jun 23, 2009 at 1:59 PM, Benoit Jacob<jacob.benoit.1@xxxxxxxxx> wrote:2009/6/23 Tim Hutt <tdhutt@xxxxxxxxx>:I think the default behavior of Eigen/FFT should favor correctness and generality over speed.1) Scaling:Other libraries (FFTW,IMKL,KISSFFT) do not perform scaling, so there is a constant gain incurred after the forward&inverse transforms , so IFFT(FFT(x)) = Kx; this is done to avoid a vector-by-value multiply. The downside is that algorithms that worked correctly in Matlab/octave don't behave the same way once implemented in C++.Simple solution, have FFT(x) and FFT_unscaled(x). That way people won't be surprised by the results but they can still be optimised+1if there is no true advantage in knowing that at compile time, I'd prefer to see only one function: FFT(..., int options = 0) possible usages: FFT(x), FFT(x, Eigen::Unscaled), ... I'm sure needs for other options will come. gael

There's at least two needed options:

and maybe

**References**:**[eigen] Eigen/FFT***From:*Mark Borgerding

**Re: [eigen] Eigen/FFT***From:*Benoit Jacob

**Re: [eigen] Eigen/FFT***From:*Mark Borgerding

**Re: [eigen] Eigen/FFT***From:*Benoit Jacob

**Re: [eigen] Eigen/FFT***From:*Tim Hutt

**Re: [eigen] Eigen/FFT***From:*Benoit Jacob

**Re: [eigen] Eigen/FFT***From:*Gael Guennebaud

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