 Functions and CALL Routines

# FNONCT Function

Returns the value of the noncentrality parameter of an F distribution.
 Category: Mathematical

## Syntax

 FNONCT(x,ndf,ddf,prob)

### Arguments

x

is a numeric random variable.

 Range: x 0
ndf

is a numeric numerator degree of freedom parameter.

 Range: ndf > 0
ddf

is a numeric denominator degree of freedom parameter.

 Range: ddf > 0
prob

is a probability.

 Range: 0 < prob < 1

The FNONCT function returns the nonnegative noncentrality parameter from a noncentral F distribution whose parameters are x, ndf, ddf, and nc. If prob is greater than the probability from the central F distribution whose parameters are x, ndf, and ddf, a root to this problem does not exist. In this case a missing value is returned. A Newton-type algorithm is used to find a nonnegative root nc of the equation where where I (. . .) is the probability from the beta distribution that is given by If the algorithm fails to converge to a fixed point, a missing value is returned.

```data work;
x=2;
df=4;
ddf=5;
do nc=1 to 3 by .5;
prob=probf(x,df,ddf,nc);
ncc=fnonct(x,df,ddf,prob);
output;
end;
run;
proc print;
run;```

```
OBS    x    df    ddf     nc      prob     ncc
1     2     4     5     1.0    0.69277    1.0
2     2     4     5     1.5    0.65701    1.5
3     2     4     5     2.0    0.62232    2.0
4     2     4     5     2.5    0.58878    2.5
5     2     4     5     3.0    0.55642    3.0``` Previous Page | Next Page | Top of Page