I became one of the 15c collecting Crowd

[Johnh]

Congrats on your new machine.

But I don't blame it for having trouble with that integral, given that the function gets up to 6.4 x 10^93 . That's not a number that comes up very often in day-to-day engineering. And in the last 5% of the x range, the function is increasing at a crazy rate. Very difficult for the algorithm to converge to what it thinks is adequate accuracy.

Still, I guess it's an extreme case . Do we know what the true result is?

I've also been exploring the integrate function. A nice simple one is to integrate a quarter of a circle of radius 2, for which the result is Pi.

y= (4-x^2)^0.5 with x from 0 to 2

It can also be numerically challenging if high accuracy is needed, since the function goes vertical as x approaches 2.

The more sig figs in the FIX display setting you ask for, the longer it takes. Using Touch 15i on my Samsung S22 and display FIX8, it took 50 seconds to arrive at Pi to 7 decimal places with the last digit 5 instead of 6. That's with the emulator set to mimic the speed of an original hp15C. It took about a second at full speed.

On a real calc, it took about a second on my hp15C CE, with the same result.