nklein software

I released version 1.3 of my Common Lisp Fourier Transform library today. It is significantly faster than yesterday’s version. On my MacBook Pro in SBCL 1.0.30 with a 512 by 512 by 16 array, version 1.3 takes 3.74 seconds where version 1.2 took 9.77 seconds and version 1.0 took 25.31 seconds. For a breakdown of performance on various array sizes with various Lisp implementations, see the performance section of the library page.

Most of the speed improvement in this version came from memory improvements. Version 1.3 doesn’t cons at all in SBCL during the processing of each row. Version 1.2 inadvertently consed three rows worth of complex numbers for every row transformed.

My library is still about 25% slower than Bordeaux FFT for one-dimensional arrays. My library, however, has full support for multi-dimensional arrays where Bordeaux-FFT does not.

I also included some validation test cases using NST to this release. To try them, go to the library directory, hop in your Lisp, and load regression.lisp.

I released version 1.2 of my Common Lisp Fourier Transform library today. It is significantly faster than the old version. On my MacBook Pro in SBCL 1.0.30 with a 512 by 512 by 16 array, version 1.2 takes 9.77 seconds where version 1.0 took 25.31 seconds. Version 1.2 consed 2.4M while version 1.0 consed 7.4M. Neither version should have to cons nearly that much, so there’s still work to be done.

This release is significantly faster under Clozure64 1.3-r11936, too. For a 512 by 512 array, version 1.2 takes 2.72 seconds (single-threaded) and 2.07 seconds (multi-threaded) where version 1.0 took 4.45 seconds (single-threaded) and 3.06 seconds (multi-threaded).

My library is still about 1/2 to 1/3 the speed of Bordeaux FFT and still allocates memory in situations that Bordeaux does not. Hopefully, I can close those gaps most of the way soon.