Difference between revisions of "Documentation/How Tos/Calc: LOGNORMDIST function"
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: <tt>'''LOGNORMDIST'''</tt> calculates the cumulative density function for a lognormal distribution. | : <tt>'''LOGNORMDIST'''</tt> calculates the cumulative density function for a lognormal distribution. | ||
| − | : <tt>'''LOGNORMDIST(x; μ; σ;)'''</tt> is equivalent to <tt>'''NORMDIST((LN(x)-μ)/σ; 0; 1; 1)'''</tt>; it may also be calculated from | + | : <tt>'''LOGNORMDIST(x; μ; σ;)'''</tt> is equivalent to <tt>'''NORMDIST((LN(x)-μ)/σ; 0; 1; 1)'''</tt>; it may also be calculated from |
| + | : <tt>'''0.5 * ERFC((-LN(x)+μ)/(σ*SQRT(2)))'''</tt> | ||
| + | : The function [[Documentation/How_Tos/Calc: ERFC function|ERFC]] belongs to the category ''Add-in''. | ||
=== Example: === | === Example: === | ||
Revision as of 22:39, 23 March 2009
LOGNORMDIST
Calculates values for the cumulative distribution function of a lognormal distribution.
Syntax:
LOGNORMDIST(x; μ; σ;)
- A variable is lognormally distributed if its natural logarithm is normally distributed. Parameters of the distribution are μ (mean) and σ (standard deviation).
- LOGNORMDIST calculates the cumulative density function for a lognormal distribution.
- LOGNORMDIST(x; μ; σ;) is equivalent to NORMDIST((LN(x)-μ)/σ; 0; 1; 1); it may also be calculated from
- 0.5 * ERFC((-LN(x)+μ)/(σ*SQRT(2)))
- The function ERFC belongs to the category Add-in.
Example:
LOGNORMDIST(1; 0; 1)
- returns 0.5.
Issues:
- In the forthcoming international standard ODFF this function has an extra parameter, allowing calculation of the probability density function as well.
