NAG Library Function Document
nag_rand_chi_sq (g05sdc) generates a vector of pseudorandom numbers taken from a -distribution with degrees of freedom.
||nag_rand_chi_sq (Integer n,
The distribution has PDF (probability density function)
This is the same as a gamma distribution with parameters
One of the initialization functions nag_rand_init_repeatable (g05kfc)
(for a repeatable sequence if computed sequentially) or nag_rand_init_nonrepeatable (g05kgc)
(for a non-repeatable sequence) must be called prior to the first call to nag_rand_chi_sq (g05sdc).
Kendall M G and Stuart A (1969) The Advanced Theory of Statistics (Volume 1) (3rd Edition) Griffin
Knuth D E (1981) The Art of Computer Programming (Volume 2) (2nd Edition) Addison–Wesley
n – IntegerInput
On entry: , the number of pseudorandom numbers to be generated.
df – IntegerInput
On entry: , the number of degrees of freedom of the distribution.
state – IntegerCommunication Array
, of this array is dictated by the requirements of associated functions that must have been previously called. This array MUST be the same array passed as argument state
in the previous call to nag_rand_init_repeatable (g05kfc)
or nag_rand_init_nonrepeatable (g05kgc)
On entry: contains information on the selected base generator and its current state.
On exit: contains updated information on the state of the generator.
x[n] – doubleOutput
On exit: the pseudorandom numbers from the specified -distribution.
fail – NagError *Input/Output
The NAG error argument (see Section 3.6
in the Essential Introduction).
6 Error Indicators and Warnings
On entry, argument had an illegal value.
On entry, .
On entry, .
An internal error has occurred in this function. Check the function call and any array sizes. If the call is correct then please contact NAG
On entry, state
vector has been corrupted or not initialized.
8 Parallelism and Performance
nag_rand_chi_sq (g05sdc) is threaded by NAG for parallel execution in multithreaded implementations of the NAG Library.
Please consult the Users' Note
for your implementation for any additional implementation-specific information.
The time taken by nag_rand_chi_sq (g05sdc) increases with .
This example prints five pseudorandom numbers from a
-distribution with five degrees of freedom, generated by a single call to nag_rand_chi_sq (g05sdc), after initialization by nag_rand_init_repeatable (g05kfc)
10.1 Program Text
Program Text (g05sdce.c)
10.2 Program Data
10.3 Program Results
Program Results (g05sdce.r)