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Action:
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Evaluates a given law or law expression with the specified input and returns a position or a par-pos.
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Filename:
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kern/kern_scm/law_scm.cxx
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Syntax:
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(law:eval-position law input)
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Arg Types:
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law
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law | string | real | position |
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par-pos | gvector
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input
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(entity | (entity ...)) | real | gvector |
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position | par-pos
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Returns:
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position | par-pos
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Errors:
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The law must return 2 or 3 values.
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Description:
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This Scheme extension evaluates the
law at the given input. It is the same as
law:eval except that it returns either a
position or a
par-pos instead of a real or list of reals. The output dimension of
law has to be two (2) or three (3). The result is a
par-pos when the output dimension is two, and
position when it is three.
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law can be a
law Scheme type or a string enclosed by double quotation marks.
law can be any combination of law functions.
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input specifies the value(s) for evaluating the law.
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Example:
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; law:eval-position
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; Create a new law.
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(define law1 (law "vec(x,x^2,-cos(x))"))
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;; law1
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; Evaluate the given law at 1.5 radians
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(law:eval-position law1 2)
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;; #[position 2 4 0.416146836547142]
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(define law2 (law "vec(x^2, y, 3 * z)"))
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;; law2
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; Evaluate the second law at some input values.
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(law:eval-position law2 (list 2 3 4))
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;; #[position 4 3 12]
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(define law3 (law "vec(a3^2,a2,a4)"))
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;; law3
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; When evaluating this, the law function has 4 as its
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; highest input index. Thus, the input list has to
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; have at least four items. In law3, input A1 is
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; not used in the law function, so the first element
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; of list is not used.
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; a3=3, a2=2, and a4=4. (a1=1).
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(define law4 (law "vec(a3^2,a4)"))
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;; law4
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(law:eval-position law3 (list 1 2 3 4))
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;; #[position 9 2 4]
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(law:eval law3 (list 1 2 3 4))
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;; (9 2 4)
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(law:eval-position law4 (list 1 2 3 4))
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;; #[par-pos 9 4]
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