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Built-in functions: dies_of function

 

 

dies_of function

dies_of(X)

Returns true if argument is the loss channel that will cause the individual to disappear at the end of the current time step.

Input: value from a loss channel in the local submodel

Result: boolean

Built-in functions: at_init function

at_init function

at_init(X)

Returns the value the argument had when first used, i.e., on model reset or when the submodel instance containing this equation was created.

at_init(X) creates an implicit intermediate result, which has the same dimensions as its argument. So if this result is implicitly replicated elsewhere in the equation, the same value will be used each time. See makearray for behaviour in explicit replication.

Built-in functions: rankings function

rankings function

Takes an array of numeric values, and returns an array with the ranks of the corresponding elements in the argument. This is 1 for the largest element, and equal to the size of the array for the smallest.

Example:

rankings([1,9,2,10,3,8,5]) -> [7,2,6,1,5,3,4]

Built-in functions: subtotals function

subtotals function

Takes an array of numeric values, and returns an array containing the running totals from summing the elements in the original array.

Example:

subtotals([1,9,2,10,3,8,5]) -> [1,10,12,22,25,33,38]

In: Contents >> Working with equations >> Functions >> Built-in functions

Built-in functions: preceding function

preceding function

preceding(T)

Takes an argument T that is a member of an enumerated type, and returns the previous member of the enumerated type.

Input: enumerated type member, or array of enumerated type members

Result: enumerated type member, or array of enumerated type members

Examples:

If enumerated type "fruit" is defined as "apple", "grape", "banana":

preceding("grape") --> "apple"

Built-in functions : following function

 

following function

following(T)

Takes an argument T that is a member of an enumerated type, and returns the next member of the enumerated type.

Input: enumerated type member, or array of enumerated type members

Result: enumerated type member, or array of enumerated type members

Examples:

If enumerated type "fruit" is defined as "apple", "grape", "banana":

following("apple") --> "grape"

Built-in functions : first function

first function

first(T)

Takes an argument T that is a member of an enumerated type, and returns "true" if it is the first member of its type, and "false" otherwise.

Input: enumerated type member, or array of enumerated type members

Result: boolean, or array of boolean values

Examples:

If enumerated type "fruit" is defined as "apple", "grape", "banana":

first("apple") --> "true"

 

Built-in functions : sgn function

sgn function

sgn(X)

Returns -1 if X is negative, or 1 if X is zero or positive

Input: numeric, or array of numeric values

Result: integer, or array of integer values

Examples:

sgn(1.9) --> 1

sgn(-1.1) --> -1

System Dynamics modelling in the Modelica modelling language

I've been looking at a number of other modelling languages, primarily to see how models are represented in the language.   One of these is Modelica, which is mainly aimed at the development of engineering-related models. A number of modelling environments, such as Dymola, are fully Modelica-compliant. 

Taxonomy upgrade extras: 

Simulistics subcontracted by Edinburgh University to work on the NitroEurope project

Further refine the B-LINE 2 model of nitrous oxide emissions from fertilised grassland (developed in earlier joint projects between the University of Edinburgh and Simulistics Ltd.) to allow it to be applied to the emission of nitrous oxide from the very wet soils of riparian buffer strips that receive high inputs of nitrate in farm drainage waters – one of the manipulations within the Grassland part of NitroEurope Component 2 – using, as previously, the Simile visual modelling environment developed by Simulistics Ltd.

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