Version 1 (modified by MarcusWalther, 15 years ago) (diff) |
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## compute crosscorrelation

**command**: CORR <wavelet> <wl-start> <wl-end> <corr-trc>

Computes crosscorrelation of two traces specified by <wavelet> and <corr-trc>. At the trace <wavelet> a time window from <wl-start> to <wl-end> is selected. This wavelet is crosscorrelated with the trace <corr-trc> from <cl-start> sec to <cl-end> sec relative to the selected wavelet window. The correlation length <cl-start>..<cl-end> is selected by the "CORRL" command (default is -30..100 sec). The output trace is positioned at the lower value of the time bound given in the "corrl" command, i.e. after a "CORRL -50 200" instruction the output traces start at time position -50.

There are three different correlation modes available. The correlation mode can be selected by "FCT CORRMODE <mode>". Mode number 1 is default.

mode description (x[i]: samples of <wavelet>, y[j]: samples of <corr-trc>)

<mode> = 1: sum_{i} (x[i]-x_mean) * (y[i]-y_mean) cc = ---------------------------------------------------------- sqrt(sum_{j}(x[j]-x_mean)^2) * sqrt(sum{k}(y[k]-y_mean)^2) <mode> = 2: sum_{i} (x[i]-x_mean) * (y[i]-y_mean) cc = ------------------------------------- sum_{j}(x[j]-x_mean)^2) <mode> = 3: sum_{i} x[i] * y[i] cc = ------------------- sum_{i} (x[i])^2

### parameters

- <par>
*parameter type: type*

explaination

- <wavelet>
*parameter type: trace*

Trace of correlation wavelet (see above).

- <wl-start>, <wl-end>
*parameter type: real*

Wavelet time window in seconds. This selected time window on trace <wavelet> is crosscorrelated with the <corr-trc> trace.

- <corr-trc>
*parameter type: trace*

The correlation waveletis correlated with this trace.

### qualifiers

- /m

The wavelet window is marked.

### example

`corr 1 100.0 110.0 4`- correlates time window from 100.0 to 110.0 sec of trace 1 with trace 4; the result is appended to the display