Predefined Constants and Math Functions

The Virtual Cell specifies a set of reserved symbols and constants and a subset of math functions that can be used in expressions and computations.

Clicking the 'Parameters and Functions' item in the 'Navigation' panel on the left of a VCell document displays the Parameters and Functions in the 'View' panel on the right. This view has 2 tabs. Clicking on the Predefined Constants and Math Functions tab displays a list of the allowed VCell constants and math functions in a table. This table is not editable. The list of symbols, constants and functions are classified as follows:

Reserved Symbols

• t - time
• x - x coord
• y - y coord
• z - z coord

Reserved Constants

• _T_ - temperature in degree Kelvin
• _PI_ - PI constant = 3.1428571428
• _F_ - Faraday constant = 9.648e4 Coloumb_per_mole
• _F_nmol_ - Faraday constant = 9.648e-5 Coulomb_per_nano-mole
• _N_pmol_ - Avagadro Number (scaled) = 6.02e11 molecules_per_pico-mole
• _K_GHK_ - Goldman-Hodgkin-Katz unit scale = 1e-9
• _R_ - Gas Constant = 8314.0 mVolts_Coulomb_per_Kelvin_per_mole
• K_millivolts_per_volt - voltage scale = 1000

Math Functions

• abs(x) - absolute value
• acos(x) - inverse cosine function
• acosh(x) - inverse hyperbolic cosine function
• acot(x) - inverse cotangent function
• acoth(x) - inverse hyperbolic cotangent function
• acsc(x) - inverse cosecant function
• acsch(x) - inverse hyperbolic cosecant function
• asec(x) - inverse secant
• asech(x) - inverse hyperbolic secant function
• asin(x) - inverse since function
• asinh(x) - inverse hyperbolic sine function
• atan(x) - inverse tangent function
• atan2(x,y) - similar to atan(y/x), except places the angle in the correct quadrant
• atanh(x) - inverse hyperbolic tangent function
• ceil(x) - smallest integral value not less than x
• cos(x) - cosine function
• cosh(x) - hyperbolic cosine function
• cot(x) - cotangent function
• coth(x) - hyperbolic cotangent function
• csc(x) - cosecant function
• csch(x) - hyperbolic cosecant function
• exp(x) - exponential function, e^x
• factorial(x) - factorial function x!
• floor(x) - largest integral value not greater than x
• log(x) - natural logarithmic function
• log10(x) - base 10 logarithmic function
• max(x,y) - maximum of x and y
• min(x,y) - minimum of x and y
• pow(x,y) - power function, x^y
• sec(x) - secant function
• sech(x) - hyperbolic secant function
• sin(x) - sine function
• sinh(x) - hyperbolic sine function
• sqrt(x) - square root
• tan(x) - tagent function
• tanh(x) - hyperbolic tangent function

Special Output Function Operators

• vcGrad(variableName,{'x','y','z','m'}) - Spatial gradient, non-membrane variable name, 'x','y','z' directions or 'm' magnitude. (include single quotes ' ')