Calculate the area under a sampled curve (or set of curves).

Given a vector (or a matrix) representing a curve (or set of curves, columnwise), the area (or set of areas) is calculated using the trapezoidal rule.

trapz(x, y)

Arguments

x	vector of samples for the dependent variable.
y	vector or matrix of samples for the independent variable. In the case of the latter, curves are organized column-wise.

Value

area (areas) under the sampled curve (curves).

Examples

x <- seq( 0, 1, by = 0.0001 )
y <- exp( x )

# Compare with true area of exp( 1 ) - 1 = 1.718282...
areaEstimate <- trapz( x, y )