Guide to Madagascar programs |
Sample output from "sfspike n1=100 | sfbandpass fhi=60 | sfattr" ******************************************* rms = 0.992354 mean = 0.987576 2-norm = 9.92354 variance = 0.00955481 std dev = 0.0977487 max = 1.12735 at 97 min = 0.151392 at 100 nonzero samples = 100 total samples = 100 ******************************************* rms = sqrt[ sum(data^2) / n ] mean = sum(data) / n norm = sum(abs(data)^lval)^(1/lval) variance = [ sum(data^2) - n*mean^2 ] / [ n-1 ] standard deviation = sqrt [ variance ]
int | lval=2 | norm option, lval is a non-negative integer, computes the vector lval-norm | |
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string | want= | 'all'(default), 'rms', 'mean', 'norm', 'var',
'std', 'max', 'min', 'nonzero', 'samples', 'short'
want= 'rms' displays the root mean square
want= 'norm' displays the square norm, otherwise specified by lval.
want= 'var' displays the variance
want= 'std' displays the standard deviation
want= 'nonzero' displays number of nonzero samples
want= 'samples' displays total number of samples
want= 'short' displays a short one-line version
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sfattr is a useful diagnostic program. It reports certain statistical values for an RSF dataset: RMS (root-mean-square) amplitude, mean value, norm value, variance, standard deviation, maximum and minimum values, number of nonzero samples, and the total number of samples.
If we denote data values as for , then the RMS value is , the mean value is , the -norm value is , the variance is , and the standard deviation is the square root of the variance. Using sfattr is a quick way to see the distribution of data values and check it for anomalies.
Guide to Madagascar programs |