PHPKonf: Istanbul PHP Conference 2017

# stats_cdf_beta

(PECL stats >= 1.0.0)

stats_cdf_betaCDF function for BETA Distribution. Calculates any one parameter of the beta distribution given values for the others.

### Descrierea

float 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 monotonicity 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.

### Parametri

`par1`

`par2`

`par3`

`which`

Integer indicating which of the next four argument values is to be calculated from the others. Legal range: 1..4 which = 1 : Calculate P and Q from X,Y,A and B which = 2 : Calculate X and Y from P,Q,A and B which = 3 : Calculate A from P,Q,X,Y and B which = 4 : Calculate B from P,Q,X,Y and A

### Valorile întoarse

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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### User Contributed Notes 2 notes

n15m0_jk
3 months ago
``` Decided to dive into the source code and provide a simple explanation:Parameters:int \$which - Select which parameter to use in the CDF Binomial calculation, based on what the prior 3 parameters are.where \$which is 4:\$arg1 = p\$arg2 = sn\$arg3 = xnreturns pr\$which = 3\$arg1 = p\$arg2 = sn\$arg3 = prreturns xn\$which = 2\$arg1 = p\$arg2 = xn\$arg3 = prreturns sn\$which = 1\$arg1 = sn\$arg2 = xn\$arg3 = prreturns p ```
Anonymous
7 years ago
``` Additional Notes, taken from source. 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          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] ```