Classpad integration (symb vs num)

[richmit Profile]

It says in the manual that the Classpad II will try to do a definite integral symbolically, and if that is not possible then it will do it numerically. This seems to work, but it can take a VERY long time for it to figure out that it can't do the symbolic integration. Sometimes it even runs out of memory before it can figure it out. For example of one that takes a long time:

integrate(sin(x)ln(x),x,0,1)

(I used "integrate" to mean the integral symbol).

An example of one that runs out of memory:

integrate(sin(x)x^2ln(x),x,0,1)

BTW, I put this second one in my HP prime. It REBOOTED! I need to load the latest firmware on that calc.

The good news is that if you know you should do a numerically, you can add a tolerance as the final argument, and the Classpad spits out the answers almost immediately.

I'm curious. Do the older classpads behave the same way, or is this just a glitch with the 1.0 software in the CPII?

[helder7]

The oldest (monochrome) Claspads work in the same way with integrals. This is not a glitch with CPII soft.

Your first exemple takes also a long time in classpad 330.

The second exemple runs out of memory. This 2nd integral is clearly quite complex, the exact value in Wolfram Alpha is integral(sin(x)x^2ln(x),x,0,1)=-3+2 gamma +3 cos(1)-2 Ci(1)+sin(1). Calculate the exact value of something like this should consume/use a lot of memory!

What I do is: when I see that the exact calculation is taking a long time (or when I do not need), I opt for an approximate calculation.

I usually insert integrals via "Interactive" > "Calculation", that makes insertion faster.