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 AEnter a number of digits (n), run the program (preferably in double precision) and the perfect result for a perfect n-digit machine will be returned.

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] 8,99999864267Now try this...

10 [A] 9,000417403

6 [A] 9,32631

3 [A] 0

0 [A]...and see what you get.

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 0and compare the result with the previous one.

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

Dieter