## grid_calculus_1-Grid_Calculator Grid Calculator

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#### Classification(s)

Geography SubjectGIScience & Remote SensingGrid Processing

#### Detailed Description

The Grid Calculator calculates a new grid based on existing grids and a mathematical formula. The grid variables in the formula begin with the letter 'g' followed by a position index, which corresponds to the order of the grids in the input grid list (i.e.: g1, g2, g3, ... correspond to the first, second, third, ... grid in list). Grids from other systems than the default one can be addressed likewise using the letter 'h' (h1, h2, h3, ...), which correspond to the 'Grids from different Systems' list.Example: sin(g1) * g2 + 2 * h1The following operators are available for the formula definition:

 + Addition - Subtraction * Multiplication / Division abs(x) Absolute Value mod(x, y) Returns the floating point remainder of x/y int(x) Returns the integer part of floating point value x sqr(x) Square sqrt(x) Square Root exp(x) Exponential pow(x, y) Returns x raised to the power of y x ^ y Returns x raised to the power of y ln(x) Natural Logarithm log(x) Base 10 Logarithm pi() Returns the value of Pi 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 min(x, y) Returns the minimum of values x and y max(x, y) Returns the maximum of values x and y gt(x, y) Returns true (1), if x is greater than y, else false (0) x > y Returns true (1), if x is greater than y, else false (0) lt(x, y) Returns true (1), if x is less than y, else false (0) x < y Returns true (1), if x is less than y, else false (0) eq(x, y) Returns true (1), if x equals y, else false (0) x = y Returns true (1), if x equals y, else false (0) and(x, y) Returns true (1), if both x and y are true (i.e. not 0) or(x, y) Returns true (1), if at least one of both x and y is true (i.e. not 0) ifelse(c, x, y) Returns x, if condition c is true (i.e. not 0), else y rand_u(x, y) Random number, uniform distribution with minimum x and maximum y rand_g(x, y) Random number, Gaussian distribution with mean x and standard deviation y xpos(), ypos() Get the x/y coordinates for the current cell col(), row() Get the current cell's column/row index ncols(), nrows() Get the number of columns/rows nodata() Returns resulting grid's no-data value

#### How to cite

SAGA (2018). grid_calculus_1-Grid_Calculator, Model Item, OpenGMS, https://geomodeling.njnu.edu.cn/modelItem/5a8ed734-dc26-4679-80c1-2b2cf046039e

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