Programming Exercise (HP-15C, 15C LE - and others)

[Gerson W. Barbosa]

(03-23-2014 08:59 AM)Thomas Klemm Wrote:  

(03-22-2014 03:02 AM)Gerson W. Barbosa Wrote:  But we can easily break the 20-second barrier on the WP 34S

Yet another idea is to combine two terms: \(\frac{1}{n}-\frac{1}{n+1}=\frac{1}{n(n+1)}\)

Code:

LBL A
0
RCL Y
DEC Z
RCL* Z
1/x
+
DSZ Y
BACK 006
END

10000
XEQ A

Code:

LBL B
INC X
*
1/x
END

9999.00102
\(\sum\) B

We don't have to deal with the alternating sign and it should be both faster and more accurate.

Cheers
Thomas

You've moved the time barrier to the 10-second line! 10.8 seconds, perhaps a few milliseconds less. The summation now takes about half the previous time, but still disappointly long: 2 min 5 sec.

Cheers,

Gerson.

P.S.: Well, not item (b) of the exercise anymore, but if all we want is just computing the sum of the first ten thousand terms of the series then we can do it in one tenth of a second (one TICK) and eleven steps at most (LBL and END included), using information available in this thread. The result will be accurate to 20 digits in double precision mode.