2.1.24.5.1.4 chi2cdf

1 Description
2 Syntax
3 Parameters
4 Return
5 Examples
6 Remark
7 See Also
8 Header to Include
9 Reference

Description

computes the lower or upper tail probability for the chi-square distribution with real degrees of freedom.

Syntax

double chi2cdf( const double x, double df, int iTail = TAILED_TEST_LOWER, int * nFail = NULL )

Parameters

x: [input] value of the Chi variate, x. must be nonnegative ( $x>=0$ ).
df: [input] degrees of freedom, df, $\nu$ of the distribution $\chi^2$ , must be positive(df>0).
iTail: [input] upper tailed, or lower tailed test.; 1 = TAILED_TEST_UPPER,; 2 = TAILED_TEST_LOWER.
nFail: [output] on successful exit, it returns the NAG error code NE_NOERROR; if an error or warning has been detected, then it returns the specific error or warning code.

Return

Returns Chi Square cdf

Examples

EX1

void chi2cdf_ex1()
{
	double x[]= {0.25, 0.5, 0.75};
	double df = 3;
	for(int ii = 0; ii<3; ii++)
		printf("%f	%f:	%f\n", x[ii], df, chi2cdf(x[ii], df));
}