Difference between revisions of "LGamma"
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== LGamma(X) == | == LGamma(X) == | ||
− | Returns the Log Gamma function of «X». Without numeric overflow, this function is exactly equivalent to <code>Ln(GammaFn(X))</code>. | + | Returns the Log [[GammaFn|Gamma function]] of «X». Without numeric overflow, this function is exactly equivalent to <code>[[Ln]]([[GammaFn]](X))</code>. |
Because the gamma function grows so rapidly, it is often much more convenient to use [[LGamma]]() to avoid numeric overflow. | Because the gamma function grows so rapidly, it is often much more convenient to use [[LGamma]]() to avoid numeric overflow. | ||
− | == | + | == LogBetaFn(x) == |
− | + | To compute <code>[[Ln]]([[BetaFn]](a,b))</code>, you should instead use | |
+ | :<code>[[LGamma]](a) + [[LGamma]](b) - LGamma(a+b)</code> | ||
+ | which is less susceptible to numeric underflow for really large values of <code>a</code> and <code>b</code>. | ||
== See Also == | == See Also == | ||
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* [[Factorial]] | * [[Factorial]] | ||
* [[Ln]] -- natural log | * [[Ln]] -- natural log | ||
+ | * [[BetaFn]] |
Latest revision as of 21:25, 5 February 2016
LGamma(X)
Returns the Log Gamma function of «X». Without numeric overflow, this function is exactly equivalent to Ln(GammaFn(X))
.
Because the gamma function grows so rapidly, it is often much more convenient to use LGamma() to avoid numeric overflow.
LogBetaFn(x)
To compute Ln(BetaFn(a,b))
, you should instead use
which is less susceptible to numeric underflow for really large values of a
and b
.
See Also
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