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To specify the probability density function to be used in the calculation of histograms.
Refer to Histogram Overview for further information on this feature.
Two lines of data specifying the probability density function as follows.
PDF=PDF Type
[Threshold Bandwidth]
PDF Type can be RAYLEIGH DIRLIK or AUTO. The Threshold Bandwidth input is only relevant if PDF Type is set to AUTO. Threshold Bandwidth must be between 0 and 1.
Input: |
Description |
Probability Density Function: |
This option allows you to choose the probability density function (PDF) to be used in the calculation of histograms. The options are Rayleigh (the default), Dirlik and Automatic. |
Threshold Bandwidth: |
The threshold bandwidth below which Histogram is to automatically use the Rayleigh PDF, and above which Dirlik’s PDF is to be used. The bandwidth must be between 0 and 1. |
(a)The Rayleigh PDF is narrow banded, while the Dirlik PDF is more appropriate when the stress spectra are broad banded.
(b)The check on whether to use the Rayleigh or Dirlik’s PDF is applied on a spectrum by spectrum basis. The bandwidth of each response spectrum (that is, of the spectrum from each analysis you specify) is individually computed, and then the check is applied. The chosen PDF is then used in calculating the contribution to the response histogram from that spectrum. Naturally if you nominate either Rayleigh or Dirlik, then that PDF is used with all response spectra.
(c)The value of the bandwidth for each individual response spectrum is echoed by Histogram to the output file, where the program also indicates which pdf is used based on the threshold you specify. This allows you to monitor or verify the program operation.