HP71B Integral Questions

[J-F Garnier]

(02-07-2020 03:49 AM)Wes Loewer Wrote:  The 50g definitely uses Romberg extrapolation of midpoints.
...
I could be wrong, but I would be very surprised if they changed up the algorithm for the 71b.

It's easy to check that the HP71 doesn't use the mid points but the trapezoid nodes, by tracing the function sampled points:

10 DEF FNF(X) @ PRINT X; @ FNF=X @ END DEF
20 I=INTEGRAL(-1,1,.00001,FNF(IVAR))

>RUN
0 -.6875 .6875 -.3671875 .3671875 -.9140625 .9140625
the sampled points corresponds to the u values of 0, +/-0.5, +/-0.25, +/-0.75.

I would be interested to know how the 48/49/50 series work. Like the HP71 math ROM, or with further improvements? (I could try but I'm not a RPL guy :-)

J-F