quantspec (version 1.0-0)

frequenciesValidator: Validates if frequencies are Fourier frequencies from $[0,\pi]$.

Description

Validation of the parameter freq is perfomed in six steps:

1. Throw an error if parameter is not a vector or not numeric.
2. Transform each element$\omega$of the vector to$[0,2\pi)$, by replacing it with$\omega \, \mbox{mod} \, 2\pi$.
3. Check whether all elements$\omega$of the vector are Fourier frequency$2 \pi j / T$,$j \in Z$. If this is not the case issue a warning and round each frequency to the next Fourier frequency of the mentioned type; the smaller one, if there are two.
4. Transform each element$\omega$with$\pi < \omega < 2\pi$of the vector to$[0,\pi]$, by replacing it with$2\pi - \omega$.
5. Check for doubles and remove all but the first appearance.
6. Sort in ascending order.

Any subset of the six steps can be chosen, but 1 should almost always be among the steps to be performed.

Usage

frequenciesValidator(freq, N, steps = 1:6)

Arguments

freq

the vector of frequencies to be validated.

N

the base of the Fourier frequencies against which the values in freq will be compared.

steps

a vector containing a subset of {1,2,3,4,5,6}, indicating which of the steps are to be performed.

Value

• Returns a vector of Fourier frequencies that is yield by the transformations described above.

Examples

freq <- 2*pi*c(3,2,5,8,9)/10

res <- frequenciesValidator(freq, N=10, steps=1:3)
res * 10 / (2*pi) # Returns: [1] 3 2 5 8 9

res <- frequenciesValidator(freq, N=10, steps=1:4)
res * 10 / (2*pi) # Returns: [1] 3 2 5 2 1

res <- frequenciesValidator(freq, N=10, steps=1:5)
res * 10 / (2*pi) # Returns: [1] 3 2 5 1

res <- frequenciesValidator(freq, N=10, steps=1:6)
res * 10 / (2*pi) # Returns: [1] 1 2 3 5