# fdata.deriv: Computes the derivative of functional data object. In fda.usc: Functional Data Analysis and Utilities for Statistical Computing

 fdata.deriv R Documentation

## Computes the derivative of functional data object.

### Description

Computes the derivative of functional data.

• If method ="bspline", "exponential", "fourier", "monomial" or "polynomial". `fdata.deriv` function creates a basis to represent the functional data. The functional data are converted to class `fd` using the `Data2fd` function and the basis indicated in the `method`. Finally, the function calculates the derivative of order `nderiv` of curves using `deriv.fd` function.

• If `method`="fmm", "periodic", "natural" or "monoH.FC" is used `splinefun` function.

• If `method`="diff", raw derivation is applied. Not recommended to use this method when the values are not equally spaced.

### Usage

```fdata.deriv(
fdataobj,
nderiv = 1,
method = "bspline",
class.out = "fdata",
nbasis = NULL,
...
)
```

### Arguments

 `fdataobj` `fdata` class object. `nderiv` Order of derivation, by defalult `nderiv`=1. `method` Type of derivative method, for more information see details. `class.out` Class of functional data returned: `fdata` or `fd` class. `nbasis` Number of Basis for `fdatataobj\\$DATA`. It is only used if method ="bspline", "exponential", "fourier", "monomial" or "polynomial" `...` Further arguments passed to or from other methods.

### Value

Returns the derivative of functional data of `fd` class if `class.out`="fd" or `fdata` class if `class.out`="fdata".

See also `deriv.fd`, `splinefun` and `fdata`

### Examples

```data(tecator)
absorp=tecator\$absorp.fdata
tecator.fd1=fdata2fd(absorp)
tecator.fd2=fdata2fd(absorp,"fourier",9)
tecator.fd3=fdata2fd(absorp,"fourier",nbasis=9,nderiv=1)
#tecator.fd1;tecator.fd2;tecator.fd3
tecator.fdata1=fdata(tecator.fd1)
tecator.fdata2=fdata(tecator.fd2)
tecator.fdata3=fdata(tecator.fd3)
tecator.fdata4=fdata.deriv(absorp,nderiv=1,method="bspline",
class.out='fdata',nbasis=9)
tecator.fd4=fdata.deriv(tecator.fd3,nderiv=0,class.out='fd',nbasis=9)
plot(tecator.fdata4)
plot(fdata.deriv(absorp,nderiv=1,method="bspline",class.out='fd',nbasis=11))

```

fda.usc documentation built on Oct. 17, 2022, 9:06 a.m.