Index: /trunk/doc/pslib/ChangeLogSDRS.tex =================================================================== --- /trunk/doc/pslib/ChangeLogSDRS.tex (revision 2187) +++ /trunk/doc/pslib/ChangeLogSDRS.tex (revision 2188) @@ -1,3 +1,3 @@ -%%% $Id: ChangeLogSDRS.tex,v 1.36 2004-10-21 21:54:57 price Exp $ +%%% $Id: ChangeLogSDRS.tex,v 1.37 2004-10-21 22:40:25 price Exp $ \subsection{Changes from version 00 to version 01} @@ -352,3 +352,5 @@ \item In \code{psVectorStats} and \code{psVectorHistogram}, the \code{errors} vector must be of the same type as the input values vector. +\item Added \code{psLookupTable} section, and removed + \code{psTimeTableInterpolate} (now redundant). \end{itemize} Index: /trunk/doc/pslib/psLibSDRS.tex =================================================================== --- /trunk/doc/pslib/psLibSDRS.tex (revision 2187) +++ /trunk/doc/pslib/psLibSDRS.tex (revision 2188) @@ -1,3 +1,3 @@ -%%% $Id: psLibSDRS.tex,v 1.139 2004-10-21 21:55:03 price Exp $ +%%% $Id: psLibSDRS.tex,v 1.140 2004-10-21 22:39:57 price Exp $ \documentclass[panstarrs,spec]{panstarrs} @@ -1717,4 +1717,67 @@ \code{psHash} table as a linked list. +\subsection{Lookup Tables} + +Lookup tables store a variety of values indexed on a certain column. +An example is for storing the difference between UT1 and UTC, and the +polar motion vector as a function of date. + +\begin{verbatim} +typedef struct { + psVector *index; ///< Index values + psArray *values; ///< Corresponding values: an array of vectors +} psLookupTable; +\end{verbatim} + +\code{index} shall contain the index values, which shall be sorted in +increasing order. The \code{values} shall consist of an array of +vectors, each of the same length as the \code{index} vector. The +vectors (including the \code{index} and all vectors in the +\code{values} array) may be any numerical type except complex types. + +The constructor shall be: +\begin{verbatim} +psLookupTable *psLookupTableAlloc(int numValues); +\end{verbatim} +Here the \code{numValues} indicates the number of vectors in the +\code{values} array. + +The destructor shall also free the components. + +\begin{verbatim} +psLookupTable *psLookupTableRead(const char *filename, int numValues); +\end{verbatim} +\code{psLookupTableRead} shall read the file specified by +\code{filename} and import the data into a \code{psLookupTable}. The +file shall be plain text, with index and values on separate lines, +separated by whitespace. Lines commencing with a comment character +(the pound sign, \code{#}) and blank lines shall be ignored. +\code{numValues} in addition to the index shall be read on each line. +If the \code{index} vector is not sorted in the file, the lookup table +shall be sorted prior to the function returning, but no sort shall be +performed if the indices were sorted in the file. + +Interpolation on a lookup table is performed by the following +functions: +\begin{verbatim} +psF64 psLookupTableInterpolate(psLookupTable *table, psF64 index, int column); +psVector *psLookupTableInterpolateAll(psLookupTable *table, psF64 index); +\end{verbatim} +Both functions shall interpolate the \code{table} at the provided +\code{index}. For \code{psLookupTableInterpolate}, only the value in +the specified \code{column} shall be calculated and returned. For +\code{psLookupTableInterpolateAll}, all the values shall be calculated +and returned as a \code{psVector}, the type of which shall be +\code{PS_TYPE_F64}. If the \code{index} is beyond the range of the +\code{table}, \code{psLookupTableInterpolate} shall return \code{NaN}, +and \code{psLookupTableInterpolateAll} shall return \code{NULL} --- +that is, no attempt is made at extrapolation. + + + + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + \section{Data manipulation} @@ -1732,6 +1795,4 @@ \item Minimization and fitting routines. \end{itemize} - -%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \subsection{BitSets} @@ -3410,8 +3471,6 @@ PSLib). The format of these files shall be simple, for speed in reading: Each line shall contain the MJD, $x_p$ (in arcseconds), $y_p$ -(in arcseconds) and $\Delta$UT (in seconds) separated by whitespace; -blank lines and lines commencing with the comment character (the hash -symbol, \code{#}) as the first character shall be ignored. For -example: +(in arcseconds) and $\Delta$UT (in seconds) in a format readable by +\code{psLookupTableRead}. For example: \begin{verbatim} @@ -3446,8 +3505,5 @@ const char *filename; // Filename of time table const psF64 validFrom, validTo; // MJDs of validity of time table - bool loaded; // Has the table been loaded? - psVector *mjd; // MJD data, type is psF64 - psVector *dut; // delta UT = UT1 - UTC data - psVector *xp, *yp; // Polar motion data + psLookupTable *table; // Lookup table indexed on MJD, with UT1-UTC, xp and yp } psTimeTable; \end{verbatim} @@ -3473,19 +3529,19 @@ \end{verbatim} -Given a time \code{table} and a Modified Julian Date, \code{mjd}, at -which to interpolate values, \code{psTimeTableInterpolate} shall -calculate the appropriate UT1-UTC (\code{dut}; if non-\code{NULL}), -and polar motion (\code{xp,yp}; if non-\code{NULL}) by interpolation -on the table. If the \code{mjd} is outside the range of the table or -the interpolation was for some other reason unsuccessful, then the -function shall return \code{false}; otherwise the function shall set -those parameters which are non-\code{NULL} (\code{dut,xp,yp}) and -return \code{true}. If the requested \code{mjd} lies in the range of -the \code{table}, but the \code{table} has not been \code{loaded}, -then the function shall call \code{psTimeTableLoad}. -\begin{verbatim} -bool psTimeTableInterpolate(const psTimeTable *table, double *xp, - double *yp, double *dut, psF64 mjd); -\end{verbatim} +%Given a time \code{table} and a Modified Julian Date, \code{mjd}, at +%which to interpolate values, \code{psTimeTableInterpolate} shall +%calculate the appropriate UT1-UTC (\code{dut}; if non-\code{NULL}), +%and polar motion (\code{xp,yp}; if non-\code{NULL}) by interpolation +%on the table. If the \code{mjd} is outside the range of the table or +%the interpolation was for some other reason unsuccessful, then the +%function shall return \code{false}; otherwise the function shall set +%those parameters which are non-\code{NULL} (\code{dut,xp,yp}) and +%return \code{true}. If the requested \code{mjd} lies in the range of +%the \code{table}, but the \code{table} has not been \code{loaded}, +%then the function shall call \code{psTimeTableLoad}. +%\begin{verbatim} +%bool psTimeTableInterpolate(const psTimeTable *table, double *xp, +% double *yp, double *dut, psF64 mjd); +%\end{verbatim} \paragraph{Time Metadata}