R: Search for existing ipndacw matrices.

rmget {wavethresh} | R Documentation

## Search for existing ipndacw matrices.

### Description

Returns the integer corresponding to the smallest order `ipndacw` matrix of greater than or equal to order than the order, J requested.

Not really intended for user use.

### Usage

    rmget(requestJ, filter.number, family)

### Arguments

`requestJ` | A positive integer representing the order of the `ipndacw` matrix that is required.
`filter.number` | The index number of the wavelet used to build the `ipndacw` matrix that is required.
`family` | The wavelet family used to build the `ipndacw` matrix that is required.

### Details

Some of the matrices computed by `ipndacw` take a long time to compute. Hence it is a good idea to store them and reuse them.

This function is asked to find an `ipndacw` matrix of a particular order, filter.number and family. The function steps through all of the directories in the `search()` list collecting names of all `ipndacw` matrices having the same filter.number and family characteristics. It then keeps any names where the order is larger than, or equal to, the requested order. This means that a suitable `ipndacw` matrix of the same or larger order is visible in one of the `search()` directories. The matrix name with the smallest `order` is selected and the order of the matrix is returned. The routine that called this function can then `get()` the matrix and either use it "as is" or extract the top-left hand corner of it if `requestJ` is less than the order returned by this function.

If no such matrix, as described by the previous paragraph, exists then this function returns `NULL`.

This function calls the subsidiary routine `firstdot`.

### Value

If a matrix of order larger than or equal to the requested order exists somewhere on the search path and the `filter.number` and `family` is as specified then its order is returned. If more than one such matrix exists then the order of the smallest one larger than or equal to the requested one is returned.

If no such matrix exists the function returns NULL.

### RELEASE

Version 3.9 Copyright Guy Nason 1998

### Author(s)

G P Nason

### References

Nason, G.P., von Sachs, R. and Kroisandt, G. (1998). Wavelet processes and adaptive estimation of the evolutionary wavelet spectrum. Technical Report, Department of Mathematics University of Bristol/ Fachbereich Mathematik, Kaiserslautern.

### See Also

`firstdot`, `ipndacw`, `rmname`.

### Examples

    #
    # Suppose there are no matrices in the search path.
    #
    # Let's look for the matrix rm.4.1.DaubExPhase (Haar wavelet matrix of
    # order 4)
    #
    rmget(requestJ=4, filter.number=1, family="DaubExPhase")
    #NULL
    #
    # I.e. a NULL return code. So there were no suitable matrices.
    #
    #If we create two Haar ipndacw matrix of order 7 and 8
    #
    ipndacw(-7, filter.number=1, family="DaubExPhase")
    ipndacw(-8, filter.number=1, family="DaubExPhase")
    #
    # Now let's repeat the earlier search
    #
    rmget(requestJ=4, filter.number=1, family="DaubExPhase")
    #[1] 7
    #
    # So, as we the smallest Haar ipndacw matrix available larger than
    # the requested order of 4 is "7".
    #

[Package wavethresh version 4.6.8 Index]