Difference between revisions of "Mid"

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Evaluates «x» in [[Evaluation Modes|Mid-Mode]].
 
Evaluates «x» in [[Evaluation Modes|Mid-Mode]].
  
Whenever an expression or subexpression is evaluated, it is evaluated either in ''Mid-mode'' or ''Sample-mode'', in which sample-mode carries through information about uncertainty whereas mid-mode does not. The article on [[Evaluation Modes]] explains this in detail. <code>[[Mid]](x)</code> forces the evaluation of «x» to occur in Mid-mode even when the current evaluation mode is sample-mode.
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Whenever an expression or subexpression is evaluated, it is evaluated either in ''Mid-mode'' or ''Sample-mode'', in which sample-mode carries through information about uncertainty whereas mid-mode does not. The article on [[Evaluation Modes]] explains this in detail. [[Mid]](x) forces the evaluation of «x» to occur in Mid-mode even when the current evaluation mode is sample-mode.
  
The <code>[[Sample]](x)</code> function does the opposite -- forcing «x» to be evaluated in sample mode.
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The [[Sample]] function does the opposite -- forcing «x» to be evaluated in sample mode.
  
Distribution functions return their median value in Mid-mode, or a Monte Carlo when evaluated in Sample-mode.
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Distribution functions return their [[median]] value in Mid-mode, or a Monte Carlo when evaluated in Sample-mode.
  
<code>[[Mid]](x)</code> is also used as an ''meta-expression'' in a [[MultiTable]] to show the computed value of «x».
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[[Mid]] is also used as an ''meta-expression'' in a [[MultiTable]] to show the computed value of «x».
  
 
== Examples ==
 
== Examples ==
  
Suppose <code>x := Uniform(1,1)^2</code>
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Suppose <code>x := Uniform(1, 1)^2</code>
:<code>[[Mid]](x) &rarr; 0</code>
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:<code>Mid(x) &rarr; 0</code>
:<code>[[Median]](x) &rarr; 0.25</code>
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:<code>Median(x) &rarr; 0.25</code>
:<code>[[Mean]](x) &rarr; 0.3333</code>
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:<code>Mean(x) &rarr; 0.3333</code>
When [[Mid]] is evaluated, the median value of <code>Uniform(-1,1)</code> is used, which is 0 and is then squared to get the mid-value of x. As seen, this is not equivalent to the median of «x» when uncertainty is properly accounted for.
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When [[Mid]] is evaluated, the median value of <code>Uniform(-1, 1)</code> is used, which is 0 and is then squared to get the mid-value of <code>x</code>. As seen, this is not equivalent to the median of <code>x</code> when uncertainty is properly accounted for.
  
 
== See Also ==
 
== See Also ==
 
* [[Evaluation Modes]]
 
* [[Evaluation Modes]]
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* [[Median]]
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* [[Mean]]
 
* [[Sample]]
 
* [[Sample]]
 
* [[Random]]
 
* [[Random]]
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* [[Uniform]]
 
* [[Function Parameter Qualifiers]]
 
* [[Function Parameter Qualifiers]]

Revision as of 22:08, 9 May 2016


Mid(x)

Evaluates «x» in Mid-Mode.

Whenever an expression or subexpression is evaluated, it is evaluated either in Mid-mode or Sample-mode, in which sample-mode carries through information about uncertainty whereas mid-mode does not. The article on Evaluation Modes explains this in detail. Mid(x) forces the evaluation of «x» to occur in Mid-mode even when the current evaluation mode is sample-mode.

The Sample function does the opposite -- forcing «x» to be evaluated in sample mode.

Distribution functions return their median value in Mid-mode, or a Monte Carlo when evaluated in Sample-mode.

Mid is also used as an meta-expression in a MultiTable to show the computed value of «x».

Examples

Suppose x := Uniform(1, 1)^2

Mid(x) → 0
Median(x) → 0.25
Mean(x) → 0.3333

When Mid is evaluated, the median value of Uniform(-1, 1) is used, which is 0 and is then squared to get the mid-value of x. As seen, this is not equivalent to the median of x when uncertainty is properly accounted for.

See Also

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