---
name: "ncap"
section: "1"
platform: "linux"
package: "nco"
version: "4.6.3-1+b1"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/ncap"
---

# ncap(1)

netCDF Arithmetic Processor

## NAME

ncap - netCDF Arithmetic Processor

## SYNTAX

ncap \[-3\] \[-4\] \[-6\] \[-7\] \[-A\] \[-C\] \[-c\] \[-D  *dbg\_lvl*\] \[-F\] \[-f\] \[--glb *att\_name=* *att\_val*\]\] \[-h\] \[--hdf\] \[--hdr\_pad *sz\_byt*\] \[-L  *dfl\_lvl*\] \[-l  *path*\] \[--no\_tmp\_fl\] \[-O\] \[-o  *output-file*\] \[-p  *path*\] \[-R\] \[-r\] \[--ram\_all\] \[-S  *script-file*\]*\[-s* *script*\]*\[-v* *var*\[, ... \]\] *input-file \[* *output-file \]*

## DESCRIPTION

**ncap** arithmetically processes a netCDF file. However, in about 2008 **ncap** was deprecated in favor of **ncap2** which far surpasses its capabilities. **ncap will eventually be completely removed from** **NCO.** It is currently retained only because it provides an easier-to-build  arithmetic operator than **ncap2.**

The processing instructions are contained either in the  **NCO** script file  **fl.nco** or in a sequence of command line arguments. The options  **-s** (or long options  **--spt** or  **--script)** are used for in-line scripts and  **-S** (or long options  **--fl\_spt** or  **--script-file)** are used to provide the filename where (usually multiple) scripting commands are pre-stored.     **ncap** was written to perform arbitrary albebraic transformations of data and archive the results as easily as possible. Missing values are treated correctly. The results of the algebraic manipulations are called  *derived fields.*

Unlike the other operators,  **ncap** does not accept a list of variables to be operated on as an argument to  **-v.** Rather, the  **-v** switch takes no arguments and indicates that  **ncap** should output  *only* user-defined variables.  **ncap** does not accept or understand the  **-x** switch.

## EXAMPLES

Compute the square of variable  **T**

ncap -s "T2=T\*T" in.nc out.nc

## AUTHOR

**NCO** manual pages written by Charlie Zender and originally formatted by Brian Mays.

## REPORTING BUGS

Report bugs to \<http://sf.net/bugs/?group\_id=3331\>.

## COPYRIGHT

Copyright © 1995-2016 Charlie Zender\
 This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

## SEE ALSO

The full documentation for **NCO** is maintained as a Texinfo manual called the  **NCO Users Guide.** Because  **NCO** is mathematical in nature, the documentation includes TeX-intensive portions not viewable on character-based displays.  Hence the only complete and authoritative versions of the  **NCO Users Guide** are the PDF (recommended), DVI, and Postscript versions at \<http://nco.sf.net/nco.pdf\>, \<http://nco.sf.net/nco.dvi\>, and \<http://nco.sf.net/nco.ps\>, respectively. HTML and XML versions are available at \<http://nco.sf.net/nco.html\> and \<http://nco.sf.net/nco.xml\>, respectively.

If the **info** and **NCO** programs are properly installed at your site, the command

-

  **info nco**

should give you access to the complete manual, except for the TeX-intensive portions.

[**ncap**(1)](/ncap/1.md), [**ncap2**(1)](/ncap2/1.md), [**ncatted**(1)](/ncatted/1.md), [**ncbo**(1)](/ncbo/1.md), [**ncclimo**(1)](/ncclimo/1.md), [**nces**(1)](/nces/1.md), [**ncecat**(1)](/ncecat/1.md), [**ncflint**(1)](/ncflint/1.md), [**ncks**(1)](/ncks/1.md), [**nco**(1)](/nco/1.md), [**ncpdq**(1)](/ncpdq/1.md), [**ncra**(1)](/ncra/1.md), [**ncrcat**(1)](/ncrcat/1.md), [**ncremap**(1)](/ncremap/1.md), [**ncrename**(1)](/ncrename/1.md), [**ncwa**(1)](/ncwa/1.md)

## HOMEPAGE

The  **NCO** homepage at \<http://nco.sf.net\> contains more information.