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Language Reference 3

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ONE

return 1.0

  1. Number return value of the number specified

<Constant> return value of a named constant <Constant>[Expr] return value of a named vector constant <Constant>[Expr, Expr] return value of a named array constant <Macro>[Expr] return value of expression at specified index in macro


(Expr, Expr) draw a value from a normal distribution, where the first expression specifies the mean and the second specifies the standard deviation

(Expr, Expr, Expr) draw a value from a skewed normal distribution, where the first expression specifies the mode and the second and third specify the standard deviations to the left and right of the mode (Expr, Expr) draw a value from a log normal distribution, where the first expression specifies the mean and the second specifies the standard deviation of the underlying normal distribution

(Expr, Expr) draw a value from a Weibull distribution, where the first expression specifies the beta and the second specifies alpha (Note:terminology varies between sources. The version here is equivalent to that in Excel, with reversal of parameters).

OR

DESCRIPTION: A Boolean function operator that returns TRUE(1) if value of at least one expression is TRUE(1) and FALSE(0) otherwise.

USAGE: 

  x=Expr OR Expr

REQUIRED ARGUMENTS: Expr is any expression that evaluates to single numeric value

VALUE: Either TRUE(1) or FALSE(0)

SEE ALSO: Model Builder's Guide Chapter 9#Composite Functions

Example 1: 

   x=(2*8==16) OR (2>5)(TRUE)
   =1

Example 2: 

  x=(2*8!=4*4) OR (2>5) (FALSE)
   =0

<figure out an end example indicator. For example, ***>

SAMPLE MODELS: <links to sample models where this function is used>

OVER INDEX SEQUENCE

(Expr, Expr) defines linear sequence of location indices. DECISION Expr If there is a decision expression, then only those cells for which this expression returns TRUE will be included. The system variable Index holds the value of the index at each value in the sequence

Over region expressions are very frequently used to visit all cells in a landscape that meet some condition (e.g. to compute the size of the forest at initiation). Model Builder's Guide Chapter 9#Region Functions OVER RegionFunction Apply a set of sub-expressions at all spatial 

  Expression	locations specified by a region function

 : ENDFN Model Builder's Guide Chapter 9#Region Functions AT LOCATION #Expr Apply a set of state-changes at a specified 

  Expression	location

: ENDFN Model Builder's Guide Chapter 9#Region Functions

Matrix assignment is indicated using “[=]” instead of “=”. The proper dimensions of the component arrays must be met.

Variable [=] Variable assign variable of same dimension, or a single value to all entries Variable [=] Variable + Variable sum variables of same dimension (or with a constant) Variable [=] Variable - Variable subtract variables of same dimension (or with a constant) Variable [=] Variable * Variable matrix or scalar multiplication.

Variable [=] TRANSPOSE(Variable) matrix transposition Variable [=] Variable^-1 invert a matrix Variable = SUM(Variable) sum all entries in a matrix Variable [=] SUM ROWS (Variable) sum all rows of a matrix (result has one value per column) Variable [=] SUM COLS(Variable) sum all columns of a matrix

Variables [=] SORT(Variable, Expr) sort rows of an input matrix where rank is given by Expr. The system variable “Index” can appear in the expression and will take on the range of indices in the input array. The resulting sorted matrix will be assigned.

Variable [=] MPM_MULT(Variable, Variable) Performs a “matrix population model” (MPM) integer-based multiplication. Assumes that first matrix is two-dimensional and that second is a vector. The result is two-dimensional, where entries above diagonal represent "offspring", entries on the diagonal represent "survivors" and entries below the diagonal represent "succeeders"

Variable [=] CONTAG(Variable, Variable) Creates a “temporal contagion” matrix. Given probabilities (first parameter) for a set of states and a two-dimensional contagion array (values –1 to 1 indicating affinity), generates a matrix where each row is a prob. dist. For transitions given the row value, and the overall target dist. will be met. Model Builder's Guide Chapter 9#Matrix Functions

PAUSE

Halts the simulation and displays a dialog box to which the user must respond to continueModel Builder's Guide Chapter 9#Control Expressions

PAUSE IF

Expr If the expression evaluates to TRUE, halts the simulation and displays a dialog box to which the user must respond to continueModel Builder's Guide Chapter 9#Control Expressions

PAUSE

(#Value) Pauses the simulation for the specified number of milliseconds and then continuesModel Builder's Guide Chapter 9#Control Expressions

PAUSE (#Value)IF

Expr If the expression evaluates to TRUE, Pauses the simulation for the specified number of milliseconds and then continuesModel Builder's Guide Chapter 9#Control Expressions

SKEWED NORMAL CDF

(Expr, Expr, Expr, Expr) skewed normal cumulative density function, where the first expression specifies the value, the second is the mode, and the third and fourth are the left and right standard deviations Model Builder's Guide Chapter 9#Probability Density and Cumulative Density Functions

SKEWED NORMAL PDF

(Expr, Expr, Expr, Expr) skewed normal probability density function, where the first expression specifies the value, the second is the mode and the third and fourth are the standard deviations to the left and right of the mode. Model Builder's Guide Chapter 9#Probability Density and Cumulative Density Functions

SKEWED NORMAL TEMPORAL PDF

(Expr, Expr, Expr, Expr) temporal skewed normal probability density function Model Builder's Guide Chapter 9#Probability Density and Cumulative Density Functions

RECOMPUTE

Only valid in consequent expressions of ProbInit and also when ProbInit recompute flag has been set. Causes prob. surface to be recomputed before next selection Model Builder's Guide Chapter 9#Control Expressions

REGION CENTRED

(Expr, Expr [,DistanceType][,WRAPPED]) DECISION Expr defines a region centred on the current cell. If there is a decision expression, then only those cells for which this expression returns TRUE will be included.

REGION COST SURFACE

(EndLocation, MaxCost, CostSurface) DECISION Expr COST ExprModel Builder's Guide Chapter 9#Region Functions

REGION COST SURFACE

(EndLocation, MaxCost, CostSurface, LeastCostNeighbs, AnchorLoc) 

       DECISION Expr	
       COST Expr

Defines a region surrounding a cell with cumulative costs less than MaxCost. Stops growing when EndLocation is reached or all costs are greater than MaxCost. Second form also records gradient and anchor location layers. The CostSurface layer records the cumulative cost from the cost function Model Builder's Guide Chapter 9#Region Functions

REGION COST SURFACE

(EndLocation, MaxCost, CostSurface) DECISION Expr COST ExprModel Builder's Guide Chapter 9#Region Functions

REGION COST SURFACE

(EndLocation, MaxCost, CostSurface, LeastCostNeighbs, AnchorLoc) 

       DECISION Expr	
       COST Expr

Defines a region surrounding a cell with cumulative costs less than MaxCost. Stops growing when EndLocation is reached or all costs are greater than MaxCost. Second form also records gradient and anchor location layers. The CostSurface layer records the cumulative cost from the cost function Model Builder's Guide Chapter 9#Region Functions

REGION LEAST COST PATH

(StartLocation, EndLocation) DECISION Expr COST ExprModel Builder's Guide Chapter 9#Region Functions ==REGION LEAST COST PATH==(StartLocation, EndLocation, LeastCostNeighbs) DECISION ExprModel Builder's Guide Chapter 9#Region Functions ==REGION LEAST COST PATH==(StartLocation, EndLocation, LeastCostNeighbs, AnchorLoc) DECISION Expr Defines a region with cells that approximate the least-cost path between two cells. The first generates the cost function internally. The latter two use input information from a pre-computed cost surface region. Providing both the gradient and anchor location layers provides the most accurate approximation.

Iteration is a common aspect of models (even if it is very procedural). Most programming languages offer a “for-loop” of some kind. SELES presently provides “over index sequence” expressions as a slightly more declarative (although also more cumbersome) expression for iterating. While-loops can also be used. Model Builder's Guide Chapter 9#Region Functions

REGION LOCATION

(Expr) DECISION Expr 

                             defines the region consisting of a of a single
                             location index. If there is a decision 
                             expression, then only those cells for which 
                             this expression returns TRUE will be    
                             included.

REGION LOCATION LIST

(Number+) DECISION Expr 

                            defines the region consisting of a set of  a set 
                            of known location indices. If there is a 
                            decision expression, then only those cells for
                            which this expression returns TRUE will be
                            included.

REGION LOCATION LIST

(X,n) defines the region consisting of a set of n location indices stored in one-dimensional X.

REGION RECT

(Expr, Expr, Expr, Expr) defines a rectangular region. If there is a DECISION Expr decision expression defined, then only those cells for which this expression returns TRUE will be included Model Builder's Guide Chapter 9#Region Functions

==REGION VECTOR== (StartLocation, EndLocation) defines region consisting of cells along an

REGION WHOLE MAP

DECISION Expr 

                       defines the region consisting of the entire
                       landscape. If there is a decision expression,

then only those cells for which this expression returns TRUE will be included. Model Builder's Guide Chapter 9#Region Functions

RESIZE

(Variable, Expr) Changes size (number of entries) in a global variable. Values are not maintained. Useful for when size is not known prior to simulation. Model Builder's Guide Chapter 9#Control Expressions

RESPONSE

(Expr, #A, #B, #C) two-sided version of a standard response function for the value X of the first expression: if (X < A) return e^(-(X-A)^2/(2*(C^2)) else if (X > B) return e^(-(X-B)^2/(2*(C^2)) else return 1 Model Builder's Guide Chapter 9#Continuous Functions (Miscellaneous)

ROUND(Expr)

DESCRIPTION: The rounding operator

USAGE: 

  x=ROUND(Expr)

REQUIRED ARGUMENTS: Expr is any expression that evaluates to single numeric value

VALUE: Expression value rounded to the nearest integer

SEE ALSO: Model Builder's Guide Chapter 9#Expressions:

Example 1: 

  x=ROUND(0.773)
   =1

SAMPLE MODELS: <links to sample models where this function is used>

SEED()

Gets the random number seedModel Builder's Guide Chapter 9#Control Expressions

SEED

(Expr) Sets the random number seed. Value returned is next seed.Model Builder's Guide Chapter 9#Control Expressions

SETAT(Expr,PositionList,#Type)

DESCRIPTION: A Bit-Vector function that sets the value specified by the expression, at the positions in PositionList to: FALSE(0) if Type is 0, TRUE(1) if Type is 1, and flip the bits if Type=2.

USAGE: 

  (Expr,PositionList,#Type)

REQUIRED ARGUMENTS: Expr is any expression that evaluates to single numeric value PositionList is a semi-colon separated sequence of integer or ranges (lower-upper) indicating positions in the integer (0-31).

VALUE: Any integer value

SEE ALSO: Model Builder's Guide Chapter 9#Bit-Vector Functions

Example 1: 

   The PositionList 1;4-6;27 indicates bits at positions 1,4,5,6 and 27.

<figure out an end example indicator. For example, ***>

SAMPLE MODELS: <links to sample models where this function is used>

SETAT(Expr,PositionList,#Type,#Prob)

(Expr, PositionList,#Type,#Prob) Same as above, except each position is set with probability #Prob Model Builder's Guide Chapter 9#Bit-Vector Functions DESCRIPTION: A Bit-Vector function that sets the value specified by the expression, at the positions in PositionList to: FALSE(0) if Type is 0, TRUE(1) if Type is 1; flip the bits if Type=2; note that each position is set with probability #Prob.

USAGE: 

  (Expr,PositionList,#Type,#Prob)

REQUIRED ARGUMENTS: Expr is any expression that evaluates to single numeric value PositionList is a semi-colon separated sequence of integer or ranges (lower-upper) indicating positions in the integer (0-31).

VALUE: Any integer value

SEE ALSO: Model Builder's Guide Chapter 9#Bit-Vector Functions

Example 1: 

   The PositionList 1;4-6;27;30 indicates bits at positions 1,4,5,6 and 27, each associated with probability 30%.

<figure out an end example indicator. For example, ***>

SAMPLE MODELS: <links to sample models where this function is used>

SELECTAT

DESCRIPTION: A Bit-Vector function that returns FALSE(0) if none of the bits in PositionList are set in the specified expression value and TRUE(1) otherwise

USAGE: 

  (Expr,PositionList)

REQUIRED ARGUMENTS: Expr is any expression that evaluates to single numeric value PositionList is a semi-colon separated sequence of integer or ranges (lower-upper) indicating positions in the integer (0-31).

VALUE: Either FALSE(0) or TRUE(1)

SEE ALSO: Model Builder's Guide Chapter 9#Bit-Vector Functions

Example 1: 

   yet to be determined

<figure out an end example indicator. For example, ***>

SAMPLE MODELS: <links to sample models where this function is used>

SHIFT LEFT

DESCRIPTION: A Bit-Vector function that shifts value of first expression to the left by number of bits specified by second expression

USAGE: 

  SHIFT LEFT(Expr,Expr)

REQUIRED ARGUMENTS: Expr is any expression that evaluates to single numeric value

VALUE: Any integer value

SEE ALSO: Model Builder's Guide Chapter 9#Bit-Vector Functions

Example 1: 

   SHIFT LEFT(7,5) means that position 7 will be shifted to position 2

<figure out an end example indicator. For example, ***>

SAMPLE MODELS: <links to sample models where this function is used>

SHIFT RIGHT

DESCRIPTION: A Bit-Vector function that shifts value of first expression to the right by number of bits specified by second expression

USAGE: 

  SHIFT RIGHT(Expr,Expr)

REQUIRED ARGUMENTS: Expr is any expression that evaluates to single numeric value

VALUE: Any integer value

SEE ALSO: Model Builder's Guide Chapter 9#Bit-Vector Functions

Example 1: 

   SHIFT RIGHT(7,5) means that position 7 will be shifted to position 12

<figure out an end example indicator. For example, ***>

SAMPLE MODELS: <links to sample models where this function is used>

SIN

(Expr) interpret the value of the expression as an angle theta in degrees, and return sin(theta) Model Builder's Guide Chapter 9#Continuous Functions (Trigonometric Functions)

SUM

DESCRIPTION: Returns the number that is the sum of all the expressions.

USAGE: 

  x=SUM 
      Expr
      ...  
    ENDFN

REQUIRED ARGUMENTS: Expr is any expression that evaluates to single numeric value.

VALUE: the sum of all the arguments.

SEE ALSO: <a link to the composite functions section of seles modellers guide>

EXAMPLES: <add carriage return here> Example 1: 

  y = 3
  x = SUM  
        y  
        y+2  
        5  
      ENDFN

<figure out an end example indicator. For example, ***>

SAMPLE MODELS: <links to sample models where this function is used> Model Builder's Guide Chapter 9#Composite Functions

DIVIDE successive division of the sub-expressions

Model Builder's Guide Chapter 9#Composite Functions

STRICT ORDERED

same as LESS THAN Model Builder's Guide Chapter 9#Composite Functions

TAN

DESCRIPTION: The tan function operator

USAGE: 

  x=TAN(Expr)

REQUIRED ARGUMENTS: Expr is any expression that evaluates to single numeric value.

VALUE: Interpret the value of the expression as an angle theta in degrees, and return cos(theta)

SEE ALSO: <a link to the composite functions section of seles modellers guide>

Example 1: 

  x=TAN(90)
   =-286411217403671.25

<figure out an end example indicator. For example, ***>

SAMPLE MODELS: <links to sample models where this function is used> Model Builder's Guide Chapter 9#Composite Functions

UNIFORM

(Expr, Expr) draw a value from a uniform distribution, where the first expression determines the minimum value and the second determines the maximum

UNIFORM TEMPORAL PDF

(Expr, Expr, Expr) temporal uniform probability density expression Model Builder's Guide Chapter 9#Probability Density and Cumulative Density Functions

<Variable> value of an independent variable <Variable>[Expr] value of a vector global variable <Variable>[Expr, Expr] value of an array global variable Model Builder's Guide Chapter 9#Continuous Functions (Arithmetic Functions)

(Expr) value of the expression Expr + Expr sum of two expressions Expr - Expr value of the first expression minus the value of the second expression Expr * Expr product of two expressions Expr / Expr value of the first expression divided by value of the second expression Expr ^ Expr value of the first expression to the power of the value of the second expression. An nth root can be computed with1/n as the power. | Expr | absolute value of the expression

WAIT UNTIL

Expr Suspend execution until the expression returns TRUE (1). This is intended for controlling communication and synchronization with an external application. Model Builder's Guide Chapter 9#Control Expressions

WHILE

Expr While loop: process sub-expressions denoted by 

…	 “…” while the expression evaluates to TRUE

ENDFN Model Builder's Guide Chapter 9#Control Expressions

ZERO

return 0.0

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