The QFISK function returns the value x of a variable that follows the Fisk distribution
for which the probability of being smaller or equal to x is equal to the specified
percentage.
Syntax
IDAX.QFISK(DOUBLE x, DOUBLE median, DOUBLE shape)
Parameter descriptions
- percentage
- Mandatory.
- The requested limit of the percentage.
- If percentage is not in the range of 0 - 1, QFISK(percentage,median,shape) is null for all positive median
values and positive shape values.
- Min: 0.00000000001
- Max: 0.99999999999
- Data type: DOUBLE
- median
- Mandatory.
- The median value of the distribution.
- This value is also called scale.
- If median is 0 or less, QFISK(percentage,median,shape) is null for all percentage values.
- Min: 0.000000001
- Data type: DOUBLE
- shape
- Mandatory.
- The shape of the distribution.
- If shape is 0 or less, QFISK(percentage,median,shape) is null for all percentage values.
- Min: 0.000000001
- Data type: DOUBLE
The inverse Fisk distribution has the closed form QFISK(p,median,shape) = median *
(p/(1-p))^{1/shape}
Returned information
DOUBLE the point x where PFISK(x,median,shape)=percentage.