# slope¶

```Result = slope(dem)
```
dem

spatial scalar

Result

spatial scalar

## Options¶

`--unittrue` or `--unitcell` (see also notes)

`--unittrue`

horizontal and vertical scale is measured in true distance; values on dem are interpreted as real heights (default).

`--unitcell`

horizontal and vertical scale is measured in number of cell lengths; values on dem are interpreted as number of cell lengths.

## Operation¶

For each cell, calculates the slope on basis of the elevation dem of its eight nearest neighbours in a 3 x 3 cell window. The third-order finite difference method is used, proposed by Horn, also used by Skidmore. The slope on Result is given in dZ/dX, which is the increase in height (vertical direction dZ) per distance in horizontal direction (dX). This result value is often reffered to as a percentage. Thus if slope returns a value of 0.12, one says a slope value of 12 %.

## Group¶

This operation belongs to the group of Derivatives of elevation maps

## Examples¶

1. • pcrcalc
binding
Result = Result.map;
Dem = Dem.map;
initial
report Result = slope(Dem);

• python
 Result.map Dem.map  