adding time segmetns (HMS+)?? with 41CX?



#17

Hi members, sorry if this has been addressed before, I did a search and was unable to find it. I came into possession of a rather nice HP41CX that I am told can do time computations. My question is.. is there a simply way to add time segments together maintaining the HH:MM or HH:MM:SS format? For example, I'd like to be able to add :23 min to :50 min and get an answer in the format 1:13 etc... thanks all..

Sam


#18

Type the first value (0.50) and press ENTER
Type the second value (0.23) and press XEQ [Alpha] HMS+ [Alpha]
That's it

The HMS+ function works as follows (internal steps):

Take value #1
Convert to HOURS format (same as HR function)
Take value #2
Convert to HOURS format (same as HR function)
Add both values
Convert the result to HH.MMSS (same as HMS function)

On older calculators which had no HMS+ function, you needed to go step by step. But the HP41 does.


#19

Thanks, and just to be clear on that.... if the two segments were 1min23sec and 2min50sec then it would be 1.23 <enter> and 2.50 <enter> ?


#20

Quote:
and just to be clear on that.... if the two segments were 1min23sec and 2min50sec then it would be 1.23 <enter> and 2.50 <enter> ?
No, the hour has the integer part, so 1min23 sec is .0123.

#21

Sam's version should still work (except that the second <enter> has to be replaced by HMS+ in any case). It doesn't matter whether you add minutes or seconds. Both units overflow at 60. It's just a matter of interpreting the results correctly.


#22

Quote:
Sam's version should still work (except that the second <enter> has to be replaced by HMS+ in any case). It doesn't matter whether you add minutes or seconds. Both units overflow at 60. It's just a matter of interpreting the results correctly.

that makes sense... This will be an invaluable tool for flying internationally ... we have to add up (sometimes) 100+ segments on our flight plan, and if you make one mistake, it usually means starting all over..

again, thanks for the help all.

#23

If you have fractions of seconds you'll get wrong answers though.


#24

I agree, if you are talking about 100th of seconds. Has anybody ever seen 60th of seconds as a measure?


#25

Quote:
Has anybody ever seen 60th of seconds as a measure?

I didn't. Smaller time intervals were beyond scope in the times the second (hora minuta secunda) was invented. And many years later, when fractions of seconds became measurable, people attacked this problem in a handier way, inventing the millisecond.

#26

Quote:
Has anybody ever seen 60th of seconds as a measure?

I haven't either. Whole seconds have been good enough for most uses, for most of human history. After all: there are 1.3 million of them in a circle! And as Walter said, when the need and ability to measure smaller divisions came up then there were decimal computers to calculate them. When it's railroading time, you get railroads.

Still; time and angle sexicecimal measurements are beautiful pieces of tradition, and if they weren't more useful than decimal for their purposes they would have disappeared into history.

#27

Hi Sam!


in addition to the response of Andrés who was a few minutes ahead of me, consider that the time format is HH.MMSSss with ss being 10th and 100th of a second. Thus, choose FIX 6 to display the entire value.

HMS- substracts the time value in the x-register from the value in the y-register. So, you may be able now to calculate how much time Andrés was actually faster than me :-)

(DATE+ and DDAYS do the respective with dates).

HR serves to convert the "classical" time format into a decimal format with fractions of an hour. HMS does the reverse.

For reference see Section 6 (p. 65) of Volume I of the HP-41 CX Owner's Manual or Section 6 (p. 90) of the HP-41C/CV Owner's Handbook and Programming Guide.

Both, if not at hand, available at this wonderful site.



Frido

#28

Most surveyors assigned the HMS+ to the shifted + key, the HMS- to the shifted - key, and the HMS & HR to the shifted x & / keys. I met one guy that spun a lot of repeated angles. He wrote tiny "HMS times" and "HMS divided by" functions and assigned them to the respective shifted spots.
That is easier nowadays of course. The robotic gun turns the angles automatically, the pre-programmed windows CE data collector calculates the mean, and the nephew or drinking buddy of the boss drives the info back to the office to be downloaded by an office tech.
That the old manual sighting/calculate on the 41 method gives from five to 25 times the precision - and discovers any error in the field - is lost on todays middle managers.

In case you don't have the manuals for your new treasure; they are available here from Dave at the museum. The DVD comes with not only the 41CX manual but the 41C manual too, which is easier to get into for a beginner. It also contains lots of info on the various 41 systems and more than you will ever want to know about all things RPN.


#29


OWNER’S HANDBOOK AND

PROGRAMMING GUIDE

HP-41C


Hours, minutes, seconds addition (page 90).


#30

Thanks for recalling this great work d:-)


#31

Thanks again all for the great help!

#32

Both HMS* and HMS/ are in the SandMath, as a carryover from the TOMSROM :)


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