sciss / transform4s

Scala adaptation of the JTransforms FFT library originally written in Java. Mirror of

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This is a library for FFT based transformations. It is a direct translation from Java to Scala of parts of the JTransforms library (C)opyright by Piotr Wendykier. All adaptations and Scala translation (C)opyright 2020–2021 by Hanns Holger Ruz. This project is released under the GNU Lesser General Public License v2.1+.

Why? Because I need a library that can compile both the JVM and JS. In the future, compiling to Scala Native might also be useful.


  • Removed all dependencies on other Java libraries (e.g. Apache Commons FastMath, at least for now)
  • Removed API unsupported by Scala.js (e.g. Java Logging, Java concurrency). On the JVM, you can still run the algorithms multi-threaded if desired.
  • Removed the Large Array support (not needed in my case, another Java dependency).


This project builds with sbt against Scala 2.13, 2.12, Dotty (JVM) and 2.13 (Scala.js).


The following artifact is necessary as dependency:

libraryDependencies += "de.sciss" %% "transform4s" % v

The current version v is "0.1.1"


  • Currently, the number of transforms converted to Scala is very low. In the future, more and more of JTransform's classes could be added: DoubleFFT1_D, DoubleFFT2_D. Credits: The translations are mostly mechanical through IntelliJ IDEA's Java-to-Scala translator, plus a bit of manual clean-up.

  • Unit tests have not been converted yet. In other words, no guarantee that the code translation is correct (even though likely due to the mechanical process)

  • in the future, we might use Float64Array on Scala.js for better performance