2.11.2.1 cw_evaluate(Pro)
Brief Information
Compute values of a chosen wavelet at specified evaluation points
Additional Information
This feature is for OriginPro only.
Command Line Usage
1. cw_evaluate type:=dgauss param:=3 lb:=-8 ub:=8 npts:=200
2. cw_evaluate type:=morlet param:=8
3. cw_evaluate type:=maxhat npts:=50 oy:=(col(1), col(2))
X-Function Execution Options
Please refer to the page for additional option switches when accessing the x-function from script
Variables
Display
Name
|
Variable
Name
|
I/O
and
Type
|
Default
Value
|
Description
|
| Wavelet Type
|
type
|
Input
int
|
morlet
|
Specify the type of wavelet.
Option list
- morlet:Morlet
- The Morlet wavelet.
- dgauss:DGauss
- The Derivative of a Gaussian wavelet.
- mexhat:MexHat
- The Mexican Hat Wavelet.
|
| Wave Number
|
param
|
Input
int
|
5
|
If wavelet type is Morlet, this variable specifies the wave number, which should be not less than 5 and not larger than 20. If wavelet type is DGauss, this variable specifies the order of derivative, which should be a positive integer less than 9.
|
| Lower Bound
|
lb
|
Input
double
|
-10
|
Specify the lower bound of evaluation points
|
| Upper Bound
|
ub
|
Input
double
|
10
|
Specify the upper bound of evaluation points
|
| Points of Wavelet Function
|
npts
|
Input
int
|
100
|
Specify the number of evaluation points
|
| Wavelet Function
|
oy
|
Output
XYRange
|
<new>
|
Specify the output range
See the syntax here.
|
Description
This X-Function computes the values of the chosen wavelet at the supplied evaluation points. The number of evaluation points is specified by user. And the range of the evaluation points is determined by the lower bound and upper bound.
You can use this function to evaluate three wavelet types, including Morlet, Mexican Hat and the derivative of Gaussian wavelets. See below for their definition.
The Morlet wavelet is defined as:
where k is the wave number.
The Mexican Hat wavelet is:
And the Gaussian wavelet is the pth derivative of the Gaussian function, which is defined as:
where p is the derivative order.
Examples
1. To computes the values of Mexican Hat wavelet for 150 evaluation points range from -8 to 7, use the following script command:
cw_evaluate type:=2 lb:=-8 ub:=7 npts:=150
2. To change the wavelet type, you can either use the Type drop-down list in the dialog, which can be open by typing in the command Window:
cw_evaluate -d;
Or specify which type of wavelet to use from the script line by typing, for example
cw_evalute type:=1
Algorithm
The computation is implemented with three NAG functions: nag_morlet(), nag_dgauss() and nag_mexhat().
References
Torrence, C and Compo, G... 1998. A practical guide to wavelet analysis, Bull. Amer. Meteor. Soc.
Ingrid Daubechies. 1992. Ten Lectures On Wavelets. SIAM.
Related X-Functions
dwt, idwt
|