Cumulative distribution functions: cdf

### 8.4.20 Cumulative distribution functions: cdf

The cdf command finds the cumulative distribution function for a probability distribution.

- cdf takes one or more mandatory arguments and one optional argument.
  - distd, the name of the function that finds the distribution’s density function.
  - parameters, any parameters that would normally be passed to distd.
  - x, a number.
- cdf(distd,parameters) returns an expression for the cumulative distribution function for distd with parameters parameters.
- cdf(distd,parameters,x) returns the value of the cumulative distribution function at x. parameters.

#### Examples

- Input:
  cdf(normald,0,1)
  Output:

  erf | ⎛ ⎜ ⎜ ⎝ |
  1
  2
  | x | √ |
  2
  | ⎞ ⎟ ⎟ ⎠ | +1
  2

- Input:
  cdf(binomial,10,0.5,4)
  Output:

  0.376953125