Module Grid Calculator

The Grid Calculator calculates a new grid based on existing grids and a mathematical formula. The grid variables are single characters which correspond in alphabetical order to the grid list order ('a' = first grid, 'b' = second grid, ...)
Alternatively you can address with letter 'g' followed by position index (g1, g2, g3, ...). Grids from other systems are addressed similarly, just using letter 'h' (h1, h2, h3, ...)
Examples:
using letters: sin(a) * b + c
the same using indices: sin(g1) * g2 + g3

The following operators are available for the formula definition:
+ Addition
- Subtraction
* Multiplication
/ Division
^ power
abs(x) - absolute value
sqrt(x) - square root
ln(x) - natural logarithm
log(x) - base 10 logarithm
exp(x) - exponential
sin(x) - sine
cos(x) - cosine
tan(x) - tangent
asin(x) - arcsine
acos(x) - arccosine
atan(x) - arctangent
atan2(x, y) - arctangent of x/y
gt(x, y) - if x>y the result is 1.0, else 0.0
lt(x, y) - if x<y the result is 1.0, else 0.0
eq(x, y) - if x=y the result is 1.0, else 0.0
mod(x, y) - returns the floating point remainder of x/y
ifelse(c, x, y) - if c=1 the result is x, else y
int(x) - integer part of floating point value x
pi() - returns the value of Pi
xpos(), ypos() - get the x/y coordinates of the current cell
row(), col() - get the current cell's column/row index

Author: A.Ringeler (c) 2003
Specification: grid
Menu: Grid|Calculus

Parameters

	Name	Type	Identifier	Description	Constraints
Input	Grids (*)	Grid list (optional input)	`GRIDS`	in the formula these grids are addressed in order of the list as 'g1, g2, g3, ...'	-
Input	Grids from different Systems (*)	Grid list (optional input)	`XGRIDS`	in the formula these grids are addressed in order of the list as 'h1, h2, h3, ...'	-
Output	Result	Grid (output)	`RESULT`	-	-
Options	Formula	Text	`FORMULA`	-	Default: (g1 - g2) / (g1 + g2)
	Name	Text	`NAME`	-	Default: Calculation
	Take Formula	Boolean	`FNAME`	-	Default: 0
	Use NoData	Boolean	`USE_NODATA`	Check this in order to include NoData cells in the calculation.	Default: 0
	Data Type	Choice	`TYPE`	-	Available Choices: [0] bit [1] unsigned 1 byte integer [2] signed 1 byte integer [3] unsigned 2 byte integer [4] signed 2 byte integer [5] unsigned 4 byte integer [6] signed 4 byte integer [7] 4 byte floating point number [8] 8 byte floating point number Default: 7
(*) optional

Command-line

Usage: saga_cmd grid_calculus 1 [-GRIDS <str>] [-XGRIDS <str>] [-RESULT <str>] [-FORMULA <str>] [-NAME <str>] [-FNAME <str>] [-USE_NODATA <str>] [-TYPE <str>]
  -GRIDS:<str>     	Grids
	Grid list (optional input)
  -XGRIDS:<str>    	Grids from different Systems
	Grid list (optional input)
  -RESULT:<str>    	Result
	Grid (output)
  -FORMULA:<str>   	Formula
	Text
	Default: (g1 - g2) / (g1 + g2)
  -NAME:<str>      	Name
	Text
	Default: Calculation
  -FNAME:<str>     	Take Formula
	Boolean
	Default: 0
  -USE_NODATA:<str>	Use NoData
	Boolean
	Default: 0
  -TYPE:<str>      	Data Type
	Choice
	Available Choices:
	[0] bit
	[1] unsigned 1 byte integer
	[2] signed 1 byte integer
	[3] unsigned 2 byte integer
	[4] signed 2 byte integer
	[5] unsigned 4 byte integer
	[6] signed 4 byte integer
	[7] 4 byte floating point number
	[8] 8 byte floating point number
	Default: 7