CalC ("Calcium Calculator") is a 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 is free software distributed under the terms of version 3 of the GNU General Public License.

Installation instructions: README

•  CalC version 7.0 implements cooperative calcium buffers •  CalC version x.4 implements binary file output •  CalC version x.6 implements non-linear membrane pump •  CalC version x.7 implements spherical enclosures and obstacles •  CalC version x.7.2 implements space-dependent calcium uptake •  CalC version x.8 implements arbitrary volume shapes and 2D surface plots •  CalC version x.8.4 improved and optimized adaptive time-step control •  CalC version x.9.1 important bug fix! (thanks to Christian Stricker!) •  CalC version x.9.2 bug fix in 1D data output (thanks to Morten G. Pedersen!) •  CalC version x.9.3 fixed program termination occurring before diagnostic output •  CalC version x.9.4 fixed problems with narrow off-center sources in polar variables •  CalC version x.9.5 clearly specifies GPLv3 Public License info in all source files 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

NEW: Most recent updates solve segmentation fault problems causing early termination of some simulation scripts

Version		Ca2+ buffers:	Source:		Executables:
Release 7.9.5	May 20, 2019	Cooperative	UNIX	MSDN C++	Win64	OS X 10.11.6
Release 6.9.5	May 20, 2019	Simple (faster code)	UNIX	MSDN C++	Win64	OS X 10.11.6

[ Link to full descriptions of all CalC release updates ]

Bug 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 was fixed in version x.9.1. Thanks to Christian Stricker for reporting. Click for detailed bug information

CalC Description and Features:
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 is CPU-time efficient and platform-independent (Windows, OS X, Linux, cygwin, etc.)
• CalC is operated by a simple script language with non-trivial flow control, greatly increasing its flexibility.
• CalC is easily combined with MATLAB without any special modifications (see demo).
• CalC allows simulations in any geometry: cartesian 3D, 2D or 1D, polar, spherical, cylindrical, conical, etc.
• CalC allows an arbitrary number of Ca²⁺ buffers, with 1-to-1 and 1-to-2 Ca²⁺ binding.
• CalC scripts may include ordinary differential equations, for instance to model Ca²⁺-dependent exocytosis.
• CalC results can be viewed in real time by piping the output into xmgrace (only on UNIX platforms).

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.

CalC is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the license, or (at your option) any later version. CalC is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose. See the license file for more details.

---

	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 20, 2019             Maintained by Victor Matveev