The 34s features a very useful function that rounds a value to a certain number of significant digits - the RSD function. Some time ago I wrote a short program based on the "calculator forensics" routine that determines the perfect result an n-digit calculator should return:

001 LBL A

002 STO 00

003  9

004 SIN

005 RSD->00

006 COS

007 RSD->00

008 TAN

009 RSD->00

010 ATAN

011 RSD->00

012 ACOS

013 RSD->00

014 ASIN

015 RSD->00

016 RTN

  12  [A]  8,99999864267

  10  [A]  9,000417403

   6  [A]  9,32631

   3  [A]  0

   0  [A]

Then single-step through the program and see what happens at step 012/013 where ACOS returns 90 degrees which is then rounded to 0 significant digits.

Finally try the same directly from the keyboard:

   90  RSD 0

Which leads to the question: what is RSD 0 supposed to return?

Dieter

RSD 0 is rubbish per definition. 1 is the lowest value making sense. We'll catch that bug - thanks for reporting.

d:-)

Well, in a way RSD 0 can make sense:

0,02   RSD 0  =>  0,01

0,08   RSD 0  =>  0,1

   3   RSD 0  =>  1

   6   RSD 0  =>  10

 314   RSD 0  =>  100

 628   RSD 0  =>  1000

 4999  RSD 0  =>  1000

 5000  RSD 0  =>  10000

Please also note that the current implementation may return different results in run and program mode. 90 RSD 0 here returns either 1E-14 or 10. Maybe you can check this as well.

Dieter

Edited: 27 Jan 2013, 2:07 p.m. after one or more responses were posted

In other words, RSD 0 in Dieter's mind is simply a "power of 10 orders of magnitude" function. It always returns "1. E X", where X is the appropriate order of magnitude. Or, presumably, 0.

Cheers,

Doug

If (!) RSD 0 is accepted it may behave as follows:

 SIGN

 RCL L

 STO+ X

 EXPT

 X<0?     // since SDL and SDR do not accept negative arguments

 SKIP 003 // both cases have to be handled separately

 X<>Y

 SDL->Y

 RTN

 +/-

 X<>Y

 SDR->Y

 RTN

  X      RSD 2      RSD 1      RSD 0

------------------------------------

0,333    0,33       0,3        0,1

0,877    0,88       0,9        1

314      310        300        100

682      680        700        1000

-47      -47        -50        -10

-88      -88        -90       -100

------------------------------------

Interesting continuation of the RSD function. Nevertheless I prefer stopping with RSD 1 for ... ummh ... philosophical reasons. A number can feature one or more significant digits. If it would feature zero significant digits, its overall significance would vanish. Hope this is logical.

d:-)

Rounding modes?

- Pauli

Dieter,

Quote:

---

Please also note that the current implementation may return different results in run and program mode. 90 RSD 0 here returns either 1E-14 or 10. Maybe you can check this as well.

---

d:-?

RM is 0.

Dieter

Try this (in DEG mode):

 0 ACOS   => 90

 RSD 0    => 1E-14

 

 1 ASIN   => 90

 RSD 0    => 1E-14

 

 90

 RSD 0    => 10

Finally, try this:

 0 ACOS   => 90

 0 +      => 90

 RSD 0    => 10

 

 1 ASIN   => 90

 1 x      => 90

 RSD 0    => 10

 

 90

 RSD 0    => 10

Any idea?

Dieter

Edited: 28 Jan 2013, 2:58 p.m.

Quote:

---

So, in which way is the 90 returned by ACOS different from the same value keyed in manually? ... It's hard to describe, but there seems to be some kind of ..."leftover" from the trig function that is removed with the next operation (here +0 resp. x1).

Any idea?

---

d:-)

Build 3363 doesn't allow RSD 0 anymore.

d:-)