HP 50g Calculate integral with and without EVAL

[joeres]

Hello everybody,

i would like to know why the EVAL key must be used for the calculation of the integral (https://www.integral-calculator.com/#exp...3&ubound=4): $$\int_{-3}^{4} \left | x^2-4 \right |dx$$If the EVAL key is not used (only key \->NUM), the 50g hangs up and the hourglass is displayed.

The EVAL key is not required to calculate the integral (https://www.integral-calculator.com/#exp...2&ubound=2): $$\int_{-2}^{2} \left | \sin(x) \right |dx$$The result is displayed even if I only use \->NUM.

Maybe someone has an explanation for me?

Thank you and best regards
Joerg