sddszerofind

**description:**`sddszerofind`finds the locations of zeroes in a single column of an SDDS file. This is done by finding successive rows for which a sign change occurs in the ``dependent column'', or any row for which an exact zero is present in this column. For each of the ``independent columns'', the location of the zero is determined by linear interpolation. Hence, the program is really interpolating multiple columns at locations of zeros in a single column. This single column is in a sense being looked at as a function of each of the interpolated columns.**examples:**Find zeroes of a Bessel function, :`sddszerofind J0.sdds J0.zero -zero=J0 -column=z``sddszerofind J0.sdds J0.zero -zero=J0 -column=z,J1`**synopsis:**`sddszerofind [-pipe=[input][,output]] [`*inputfile*] [*outputfile*] -zeroesOf=*columnName*[-columns=*columnNames*] [-slopeOutput]**files:***inputFile*contains the data to be searched for zeroes.*outputFile*contains columns for each of the independent quantities and a column for the dependent quantity. Normally, each dependent quantity is represented by a single column of the same name. If output of slopes is requested, additional columns will be present, having names of the form.*columnName*SlopeIf

*inputFile*contains multiple pages, each is treated separately and is delivered to a separate page of*outputFile*.**switches:**`-pipe[=input][,output]`

-- The standard SDDS Toolkit pipe option.`-zeroesOf=`-- Specifies the name of the dependent quantity, for which zeroes will be found.*columnName*`-columns=`-- Specifies the names of the independent quantities, for which zero locations will be interpolated. Generally, there is only one of these.*columnNames**columnNames*is a comma-separated list of optionally wildcarded names.`-slopeOutput`-- Specifies that additional columns will be created containing the slopes of the dependent quantity as a function of each independent quantity. This can be useful, for example, if one wants to pick out only positive-going zero-crossings.

**see also:**- sddsinterp
`sddsinterp`()sddsinterp

- sddsinterp
**author:**M. Borland, ANL/APS.