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In this section, list of recognized operators in Arithmetic (and the Table program’s Column arithmetic) and discussed in detail with examples. As mentioned before, to be able to easily do complex operations on the command-line, the Reverse Polish Notation is used (where you write ‘\(4\quad5\quad+\)’ instead of ‘\(4 + 5\)’), if you aren’t already familiar with it, before continuing, please see Reverse polish notation.

The operands to all operators can be a data array (for example a FITS image or data cube) or a number, the output will be an array or number according to the inputs. For example a number multiplied by an array will produce an array. The numerical data type of the output of each operator is described within it.

One way you can exploit this property of the NaN value to your advantage is when you want a fully zero-valued image (even over the blank pixels) based on an already existing image (with same size and world coordinate system settings). The following command will produce this for you: $ astarithmetic input.fits nan eq --output=all-zeros.fits Note that on the command-line you can write NaN in any case (for example |

- Basic mathematical operators
- Trigonometric and hyperbolic operators
- Unit conversion operators
- Statistical operators
- Stacking operators
- Filtering (smoothing) operators
- Interpolation operators
- Dimensionality changing operators
- Conditional operators
- Mathematical morphology operators
- Bitwise operators
- Numerical type conversion operators
- Adding noise operators
- Elliptical shape operators
- Building new dataset
- Operand storage in memory or a file

Next: Invoking Arithmetic, Previous: Reverse polish notation, Up: Arithmetic [Contents][Index]

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GNU Astronomy Utilities 0.16 manual, October 2021.