<casaxml xsi:schemaLocation="http://casa.nrao.edu/schema/casa.xsd file:///opt/casa/code/xmlcasa/xml/casa.xsd" xmlns="http://casa.nrao.edu/schema/psetTypes.html" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<task type="function" name="spxfit" category="analysis">
<shortdescription>Fit a 1-dimensional model(s) to an image(s) or region for determination of spectral index.</shortdescription>
<param type="any" name="imagename"><shortdescription>Name of the input image(s)</shortdescription><description>Name of the input image(s)</description>
<any type="variant" listtypes="string stringArray"/>
<example>imagename='ngc5921_task.image'</example>
<param type="string" direction="in" name="box"><shortdescription>Rectangular region to select in direction plane. Default is to use the entire direction plane.</shortdescription><description>Rectangular region to select in direction plane. Default is to use the entire direction plane.</description>
<example>box="4,4,10,10"</example>
<param type="string" direction="in" name="region"><shortdescription>Region selection. Default is to use the full image.</shortdescription><description>Region selection. Default is to use the full image.</description>
<example>region="myregion.rgn"</example>
<param type="string" direction="in" name="chans"><shortdescription>Channels to use. Default is to use all channels.</shortdescription><description>Channels to use. Default is to use all channels.</description>
<param type="string" direction="in" name="stokes"><shortdescription>Stokes planes to use. Default is to use all Stokes planes.</shortdescription><description>Stokes planes to use. Default is to use all Stokes planes.</description>
<example>stokes="I"</example>
<param type="int" direction="in" name="axis"><shortdescription>The profile axis. Default: use the spectral axis if one exists, axis 0 otherwise (<0).</shortdescription><description>The profile axis. Default: use the spectral axis if one exists, axis 0 otherwise (<0).</description>
<example>axis=3</example>
<param type="string" direction="in" name="mask"><shortdescription>Mask to use. Default is none.</shortdescription><description>Mask to use. Default is none.</description>
<param type="int" direction="in" name="minpts"><shortdescription>Minimum number of unmasked points necessary to attempt fit.</shortdescription><description>Minimum number of unmasked points necessary to attempt fit.</description>
<param type="bool" direction="in" name="multifit"><shortdescription>If true, fit a profile along the desired axis at each pixel in the specified region. If false, average the non-fit axis pixels and do a single fit to that average profile. Default False.</shortdescription><description>If true, fit a profile along the desired axis at each pixel in the specified region. If false, average the non-fit axis pixels and do a single fit to that average profile. Default False.</description>
<example>multifit=True</example>
<param type="string" direction="in" name="spxtype"><shortdescription>Type of function to fit. "plp" = power logarithmic polynomial, "ltp" = logarithmic transformed polynomial.</shortdescription><description>Type of function to fit. "plp" = power logarithmic polynomial, "ltp" = logarithmic transformed polynomial.</description>
<param type="doubleVec" name="spxest"><shortdescription>REQUIRED. Initial estimates as array of numerical values for the spectral index function coefficients. eg [1.5, -0.8] if fitting a plp function thought to be close to 1.5*(x/div)**(-0.8) or [0.4055, -0.8] if fitting an lpt function thought to be close to ln(1.5) - 0.8*ln(x/div).</shortdescription><description>REQUIRED. Initial estimates as array of numerical values for the spectral index function coefficients. eg [1.5, -0.8] if fitting a plp function thought to be close to 1.5*(x/div)**(-0.8) or [0.4055, -0.8] if fitting an lpt function thought to be close to ln(1.5) - 0.8*ln(x/div).</description>