Returns the left-tailed probability of the chi-squared distribution.
| Name | Type | Description |
| arg1 | number | The value at which the distribution will be evaluated, a nonnegative number. |
| arg2 | number | The number of degrees of freedom, a number between 1 and 10^10, excluding 10^10. |
| arg3 | boolean | A logical value that determines the form of the function. If this argument is equal to true, the cumulative distribution function is returned; if it is equal to false, the probability density function is returned. |