Content-type: text/html Manpage of ccSHTx

ccSHTx

Section: User Commands (1)
Updated: July 15 2003
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NAME

ccSHTx, ccSHTmpix - Spherical Harmonic Transform

SYNOPSIS

ccSHTx -n numPix -l lmax -f fFile -a almFile -p pixFile -d directionFlag [-w pixArea] [-q quadWeightFile] [-c]

ccSHTmpix -n numPix -l lmax -f fFile -a almFile -p pixFile -d directionFlag [-w pixArea] [-q quadWeightFile] [-c]

DESCRIPTION

These are executable applications which make use of the ccSHT spherical harmonic transform library. ccSHTx is the executable binary which performs a spherical harmonic transform in serial, and ccSHTmpix is the executable binary which does the transform in parallel. The calling sequence for these two executables is exactly the same. There are six required parameters which must be specified and two optional parameters. Please see the man page for ccSHT(1) for more information about the ccSHT package.

-n numPix: Specifies the number of pixels in the discretization of the sphere.
-l lmax: Sets the band cut off for the SHT. This is the largest value of l for which the spherical harmonic coefficients are not assumed to be zero.
-f mapFile: Specifies the name of the file which is to contain the pixel domain vector. When doing a forward transform this file is read in, and when doing a backward transform this file is created. It is formatted as a raw binary file of eight byte floating point reals or complex pairs. The pixel domain vector is assumed to be real valued unless the -c option is specified in which case the vector is interpreted as an array of complex pairs. The length of the vector is specified by the -n parameter.
-a almFile: Specifies the name of the file which is to contain the spherical harmonic coefficients. When doing a forward transform this file is created, and when doing a backward transform this file is read in. It is formatted as a raw binary file of eight byte floating point complex pairs. The number of complex pairs is (lmax+1)*(lmax+1) where lmax is specified by the -l parameter.
-p pixFile: Specifies the name of the file which contains the right ascension (RA) and declination (DEC) coordinates for each of the pixels in the discretization of the sphere. This file is formatted as a raw binary file of four byte floating point pairs of RA and DEC coordinates. There are as many coordinate pairs in this file as the number of pixels specified by the -n parameter. If there are gaps in the pixelization then an additional file may be necessary. This file must have the same name as the pixel file, only with a .dra appended to it. For instance if the pixel file was called pixels, then the additional file would be called pixels.dra. This file specifies the latitudinal spacing between pixels on every row. This file is a raw binary file. The first number in the file is a four byte integer which specifies the number of rows which are described in the file. This integer is followed by as many pairs of four byte floating point numbers. The first of each pair specifies the declination of the row, and the second specifies the change in right ascension between neighboring pixels in the given row. These pairs must be ordered in the same way as the rows in the pixel location file, but there may be more rows in the .dra file than in the pixel location file.
-d directionFlag: Specifies the direction of the transform to be performed. If (f, F, or 1) are given then the code performs a forward transform, deriving spherical harmonic coefficients from a pixel domain function. If (b, B, or -1) are given then the code performs a backward transform, deriving a pixel domain function from spherical harmonic coefficients.
-w pixArea: This optional parameter specifies the area of one pixel. This is the constant quadrature weight used to compute the integral in the forward transform. If this number is not specified, than the integral is computed as a sum, (i.e. the weight used is one). If a weight file is specified with the -q option then the -w option should not be used.
-q quadWeightFile: This optional parameter specifies a file which is to contain the quadrature weights to compute the integral in the forward transform. This file is a raw binary file of eight byte floating point numbers that specify a weight for every pixel.
-c: If this option is given then the pixel domain function is assumed to be complex valued. The pixel domain function is either the input to the forward transform or the output from the backward transform.

COPYRIGHT

Version 1.03 July 2003

ccSHTx and ccSHTmpix are free software; you can redistribute them and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

Christopher Cantalupo <cmc@nersc.gov>

Send bug reports or comments to the above address.

This document was created by man2html, using the manual pages.
Time: 23:52:28 GMT, July 15, 2003