Provides function expression of derivatives of an idealized NDVI curve fitted through a harmonic regression model
ndvi_derivatives(amp, pha, degree, L)A function expression
numeric vector specifying amplitude parameter
numeric vector specifying phase angle parameter
integer. What derivative's degree should be calculated?
degree=0 corresponds to harmonic regression fit
integer giving the number of observations per period
This function returns the derivatives of \(f(t)\), with respect to \(t\), when \(f\) has the representation:
\(f(t) = \sum_{k=1}^{p} a[i] cos( (2 \pi k t)/L - \phi[i] )\),
where \(a\) and \(\phi\) are substituted by the vectors amp
and phase, respectively. The degree of the derivative is given by the
argument degree.
phenopar, phenopar_polygon, haRmonics