Commit ff082569 authored by thomas.forbriger's avatar thomas.forbriger
Browse files

[FEATURE] (foutra): add option -derivative

This is a legacy commit from before 2015-03-01.
It may be incomplete as well as inconsistent.
See COPYING.legacy and README.history for details.

This option provides the caluclation of values representing the values for a
time series of which the derivative with time was taken. Support the
calculation of PSD for acceleration where input time series is velocity.
parent e2879b24
......@@ -51,6 +51,8 @@
* - 03/12/2014 V1.9 provide output file format selector
* - 08/01/2015 V1.10 FIX: when using -scalerbw take bandwidth from
* opt.scaledecades rather than opt.decades
* - 29/01/2015 V1.11 FEATURE: provide calculation of n-th derivative
* of time series
* \note 08/01/2010:
* Scaling for foutra power spectrum was tested against theory.
......@@ -107,8 +109,9 @@ struct Options {
bool amplitudespectrum, powerspectrum, boxcartaper;
bool avgconstbw, avgrelbw, avgasciionly;
bool demean, detrend, scalerbw, adjustdivisor;
bool derivative;
int ndemean, ndetrend, divisor;
double decades, scaledecades, asciidecades;
double decades, scaledecades, asciidecades, nderivative;
int avgsamples;
bool reportrms, harmonicsignal, padzeroes;
int padfactor, nsegments;
......@@ -142,6 +145,7 @@ int main(int iargc, char* argv[])
" [-boxcar] [-avg[=n]] [-rbw[=n]] [-avgascii]" "\n"
" [-demean[=n]] [-dtrend[=n]] [-scalerbw[=n]]" "\n"
" [-divisor[=n]] [-rms] [-harmonic] [-pad n]" "\n"
" [-derivative n]" "\n"
" [-nsegments n]" "\n"
" outfile infile [t:T] [infile [t:T] ...]" "\n"
" or: foutra --help|-h" "\n"
......@@ -173,6 +177,7 @@ int main(int iargc, char* argv[])
"-rbw[=n] smooth power spectrum by averaging over n decades" "\n"
"-demean[=n] remove average (determined from n samples)" "\n"
"-detrend[=n] remove trend (determined from n samples)" "\n"
"-derivative[=n] take n-th derivative of time series" "\n"
"-scalerbw[=n] scale to mean value in n decades" "\n"
"-divisor[=n] FFT becomes very inefficient if the factorization" "\n"
" of the number of samples includes large prime numbers." "\n"
......@@ -290,6 +295,8 @@ int main(int iargc, char* argv[])
// 22: input format
// 23: input format
......@@ -350,6 +357,8 @@ int main(int iargc, char* argv[])
TFXX_assert((opt.divisor > 0), "illegal value for argument divisor");
TFXX_assert((opt.nsegments > 0), "illegal value for argument nsegments");
......@@ -434,6 +443,15 @@ int main(int iargc, char* argv[])
if (opt.harmonicsignal || opt.amplitudespectrum || opt.powerspectrum)
processfree.append("An appropriately scaled FFT (libdrfftw) is applied");
if (opt.derivative)
processfree.append("Calculate values for derivative with respect to");
processfree.append(" time by multiplication of the Fourier coefficients");
std::ostringstream freeline;
freeline << " with the angular frequency to the power of "
<< opt.nderivative;
if (opt.amplitudespectrum)
......@@ -745,6 +763,19 @@ int main(int iargc, char* argv[])
TFXX_debug(opt.debug, "main", "create iterators");
aff::Iterator<Tseries> S(series);
aff::Browser<Tfft::Tspectrum> C(coeff);
// take derivative if selected
if (opt.derivative)
for (int i=coeff.f()+1; i<=coeff.l(); ++i)
double frequency=df*(i-coeff.f())*2*M_PI;
double thepower=opt.nderivative;
double factor=std::pow(frequency,thepower);
coeff(i) *= factor;
TFXX_debug(opt.debug, "main", "calculate square of modulus and copy");
while(S.valid() && C.valid())
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