HP Prime Graphing Calculator - Manual (Page 430)

426 Functions and commands
4. Make sure that A and B are selected and C is not.
5. Tap .
You can run your function by entering it on the entry line
in Home view, or be selecting it from the USER menu. You
enter the value for each variable you chose to be a
parameter. In this example. we chose A and B to be
parameters. Thus you might enter SINCOS(0.5, 0.75).