Pre-defined functions

The DiffSL supports the following mathematical functions that can be used in an expression:

• pow(x, y) - x raised to the power of y
• sin(x) - sine of x
• cos(x) - cosine of x
• tan(x) - tangent of x
• exp(x) - exponential of x
• log(x) - natural logarithm of x
• sqrt(x) - square root of x
• abs(x) - absolute value of x
• sigmoid(x) - sigmoid function of x
• heaviside(x) - Heaviside step function of x

You can use these functions as part of an expression in the DSL. For example, to define a variable a that is the sine of another variable b, you can write:

b { 1.0 }
a { sin(b) }

Pre-defined variables

The only predefined variable is the scalar t which is the current time, this allows the equations to be written as functions of time. For example

F_i {
  t + sin(t)
}