CalC ("Calcium Calculator") is a free (GNU copyleft) modeling tool for simulating intracellular calcium diffusion and buffering. CalC solves continuous reaction-diffusion PDEs describing the entry of calcium into a volume through point-like channels, and its diffusion, buffering and binding to calcium receptors.

•  CalC version 7.0 implements cooperative calcium buffers
•  CalC version 7.4 implements binary file output
•  CalC version 7.6 implements non-linear membrane pump
•  CalC version 7.7 implements spherical enclosures and obstacles
•  CalC version 7.7.2 implements space-dependent calcium uptake
•  CalC version 7.8 implements arbitrary volume shapes and 2D surface plots
•  CalC version 7.8.4 improved and optimized adaptive time-step control
•  CalC version 7.9.1 important bug fix!
•  CalC version 7.9.2 bug fix in 1D data output (thanks to Morten G. Pedersen!)

CalC versions 6.x.x mirror versions 7.x.x, but allow simple (1-to-1) Ca2+ buffers only, and therefore run faster; use them whenever cooperative buffers are not needed

Installation instructions: README

Beg Alert! Bug in CalC versions x.8.0-x.8.9 affects some scripts defining more than one Ca2+ channel, reducing the current through the 2nd and each consecutive Ca2+ channel. The bug is fixed in versions x.9.2 posted below. Thanks to Christian Stricker for reporting. Click for detailed bug information
VersionCa2+ buffers: Source: Executables:
Release 7.9.2 June 7, 2018 Cooperative UNIX MSDN C++ Win64 OS X 10.11.6
Release 6.9.2 June 7, 2018 Simple (faster code) UNIX MSDN C++ Win64 OS X 10.11.6
[ Link to full descriptions of all CalC release updates ]


CalC uses a variation of the Alternating Direction Implicit (ADI) finite difference method, which is very CPU-time efficient, and accurate to 2nd order in time and space. Time-step is varied adaptively during the simulation.

CalC Features:
CalC is provided on an as-is basis, but I will respond to any bug reports or technical questions, as soon as I can. If you use CalC in your published work, please cite our 2002 Biophys J article, and please send me a reference for inclusion in the CalC publication list upon publication.


Supported in part by the National Science Foundation grants 0417416, 0817703 and 1517085. However, NSF bears no responsibility for any findings, recommendations or conclusions provided by this material.
Last modified: May 2, 2018             Maintained by Victor Matveev