Integral
Function 
Integral(function)
Integral(function, start, end)
Integral(function, varName)
Integral(function, varName, start, end)

Integral is included by default in each file as part of the Math library.
See also:
Use
The Integral() function returns the integral of a function using numerical methods.
It returns the definite integral when provided with limits. It can also return the numerical approximation of the indefinite integral as a function that can be used in other equations.
The input for Integral() is given as a named custom function, or as an inline function. If no additional inputs are given, the result is a function. Otherwise, the limits can be provided, and the result is the definite integral.
Units can be used, but care must be taken that the limit inputs and the integral outputs work together.
Simple examples
Integral(x=>x^2+x+1) = Function
Integral(x=>x^2+x+1, 0, 5) = 59.167
Example using the resulting function
Definite integral example using units