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stats_cdf_beta (PECL) stats_cdf_beta -- CDF function for BETA Distribution. Calculates any one parameter of the beta distribution given values for the others. Descriptionfloat stats_cdf_beta ( float par1, float par2, float par3, int which )
Method
Cumulative distribution function (P) is calculated directly by
code associated with the following reference.
DiDinato, A. R. and Morris, A. H. Algorithm 708: Significant
Digit Computation of the Incomplete Beta Function Ratios. ACM
Trans. Math. Softw. 18 (1993), 360-373.
Computation of other parameters involve a search for a value that
produces the desired value of P. The search relies on the
monotinicity of P with the other parameter.
Note
The beta density is proportional to
t^(A-1) * (1-t)^(B-1)
Arguments
P -- The integral from 0 to X of the chi-square
distribution.
Input range: [0, 1].
Q -- 1-P.
Input range: [0, 1].
P + Q = 1.0.
X -- Upper limit of integration of beta density.
Input range: [0,1].
Search range: [0,1]
Y -- 1-X.
Input range: [0,1].
Search range: [0,1]
X + Y = 1.0.
A -- The first parameter of the beta density.
Input range: (0, +infinity).
Search range: [1D-100,1D100]
B -- The second parameter of the beta density.
Input range: (0, +infinity).
Search range: [1D-100,1D100]
STATUS -- 0 if calculation completed correctly
-I if input parameter number I is out of range
1 if answer appears to be lower than lowest
search bound
2 if answer appears to be higher than greatest
search bound
3 if P + Q .ne. 1
4 if X + Y .ne. 1
BOUND -- Undefined if STATUS is 0
Bound exceeded by parameter number I if STATUS
is negative.
Lower search bound if STATUS is 1.
Upper search bound if STATUS is 2.
Parameters
- par1
Its description
- par2
Its description
- par3
Its description
- which
Integer indicating which of the next four argument
values is to be calculated from the others.
Legal range: 1..4
iwhich = 1 : Calculate P and Q from X,Y,A and B
iwhich = 2 : Calculate X and Y from P,Q,A and B
iwhich = 3 : Calculate A from P,Q,X,Y and B
iwhich = 4 : Calculate B from P,Q,X,Y and A
Return Values
STATUS -- 0 if calculation completed correctly
-I if input parameter number I is out of range
1 if answer appears to be lower than lowest
search bound
2 if answer appears to be higher than greatest
search bound
3 if P + Q .ne. 1
4 if X + Y .ne. 1
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