PostgreSQL 把GSL库植入数据库 - GNU Scientific Library (GSL)

digoal 2020-03-26

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作者

digoal

日期

2020-03-26

背景

This Postgresql extension primarily provides wrapper functions for functions from the GNU Scientific Library (GSL) http://www.gnu.org/software/gsl/. Additional useful functions are provided to work with the wrapper functions.

This first release provides wrappers for 2 of the GSL functions, the same methods could be applied to many of the remaining 1900+ GSL functions.

The GSL library uses the system malloc(), free(), realloc() and calloc() functions and can be used with the pg_gsl extension. It is also possible to modify the GSL library to use the Postgresql memory management function palloc(), pfree() and repalloc(), details on how to make these changes is given in the later section 'Using Postgresql memory management'.

This first release wraps 2 of the 1900+ GSL functions:

pg_gsl_fft_real_transform(double precision[]) returning double precision[]

To return the transform of the input time series as the amplitudes of a series of sine and cosine waves.

pg_gsl_fft_halfcomplex_inverse(double precision[]) returning double precision[]

To return the re-constructed input time series from a set of sine and cosine waves

2 functions have been added to work with the retuned set of cosine and sine ways from pg_gsl_fft_real_transform():

pg_gsl_x_fftToSpectrum(double precision[]) returning double precision[]

To return the normalised spectrum

pg_gsl_x_fftTruncate(double precision[], n integer) returning double precision[]

To replace the last n sine and cosine waves with zeros (filtering out the higher frequencies).

and finally a function to return the extension version:

pg_gsl_x_version() returns text