Microsoft Office Tutorials and References

In Depth Information

**GAMMAINV**

GAMMAINV

GAMMAINV
returns the inverse of the gamma cumulative distribution.

=GAMMAINV(probability,alpha,beta)

The
GAMMADIST
function generates a probability
p=GAMMADIST(x,...)
. The
GAMMAINV
function

takes a probability as one of its arguments and generates x—
GAMMAINV(p,...)=x
. So that

GAMMAINV(0. 110673977,7,3)
results in 12 (when cumulative is TRUE in the
GAMMADIST

function).

Is the probability associated with the gamma distribution.

PROBABILITY

A parameter to the distribution.

ALPHA

A parameter to the distribution. If beta equals one, the standard

gamma distribution is returned.

BETA

GAMMALN

GAMMALN
returns the natural logarithm of the gamma function.

=GAMMALN(x)

For example if x=6,
GAMMALN(6)=4.787491743
.

Is the value for which you want to calculate the
GAMMALN
; must be a positive number.

X

GEOMEAN

GEOMEAN
returns the geometric mean of an array or range of positive data.

=GEOMEAN(number1,number2,...)

Use the
GEOMEAN
when you want to calculate the average growth rate of compound interest,

assuming variable interest rates. Figure 11.19 shows an example.

Up to 30 arguments can be specified, including cell references or an array.

NUMBER N

The equation for the geometric mean is