Gnuplot is a portable command-line driven graphing utility for Linux, OS/2, MS Windows, OSX, VMS, and many other platforms. The source code is copyrighted but freely distributed (i.e., you don’t have to pay for it). It was originally created to allow scientists and students to… Read more
I am relearning Fortran, including the features which have been added since I last used it some twenty years ago.Here is a method for compling a sample Fortran program NAME.F. This method checks for memory leaks.gfortran -fbounds-check -o NAME NAME.F ./NAMETom’s Fortran programs & related… Read more
Cross-correlation is a measure of similarity of two waveforms as a function of a time-lag applied to one of them. Autocorrelation is the cross-correlation of a signal with itself. It is a time domain analysis useful for determining the periodicity or repeating patterns of a… Read more
Consider a component which is to be subjected to a shock test using a shaker table. The test specification for this example is a Shock Response Spectrum (SRS). The control computer must synthesize a time history for the test. The typical method is via a… Read more
Endo & Matsuishi (1968) developed the Rainflow Counting method by relating stress reversal cycles to streams of rainwater flowing down a Pagoda. This method is very useful for fatigue analysis. The rainflow method allows the application of Miner’s rule in order to assess the fatigue… Read more
The following Matlab scripts calculate the Fourier transform of a time history: fourier.zip The main script is: fourier.m The remaining scripts are supporting functions. * * * A Matlab GUI version is included in: Vibrationdata Matlab Signal Analysis Package * * * See also: Shock… Read more
The Matlab scripts in PSD.zip calculate the power spectral density function for a time history. The main script is: PSD.m The remaining scripts are supporting functions. * * * A Fortran power spectral density program is given at: PSD.F * * * See also: Matlab Random Vibration… Read more
The most widely used algorithm for the Shock Response Spectrum (SRS) calculation for base excitation is the ramp invariant digital recursive filtering relationship given in: David O. Smallwood, An Improved Recursive Formula for Calculating Shock Response Spectra, Shock and Vibration Bulletin, No. 51, May 1981.… Read more
Here is a Fortran program which solves a system of linear equations: LIN_EQ.F It is compiled via: gfortran -o LIN_EQ LIN_EQ.F -llapack The program uses the LAPACK subroutine: DGESV * * * A version written in C/C++ is given at: linear_eq.cpp It is compiled via: gcc… Read more
Introduction Message Passing Interface (MPI) is a portable library of subprograms which can be used to facilitate parallel computing. The MPI subprograms can be called from C and Fortran programs. Parallel Computing Parallel computing enables large scale numerical problems to be solved in a timely… Read more