units anomily

05042016, 05:47 PM
Post: #1




units anomily
Version 10077, emulator
In CAS: 5_(°F)▶_(Rankine) returns "Some units could not be converted to MKSA Error: Bad Argument Value" convert(5_(°F),1_(Rankine)) returns "Some units could not be converted to MKSA Error: Bad Argument Value" While in home: 5_(°F)▶_(Rankine) returns 464.67_(Rankine) OK 5_(°F)+5_(°F) returns Error: Invalid input CAS.(5_(°F)+5_(°F)) returns (10_(°F)) OK It appears some unit operations are allowed only in CAS while other unit operations are allowed only in Home. 

05042016, 07:30 PM
(This post was last modified: 05042016 08:02 PM by informach.)
Post: #2




RE: units anomily
Hi!, roadrunner:
You can only CONVERT, for MKSA ... Meters, Kilograms, Seconds, Amperes. Converts a complex unit, into the base components, of the MKSA system. Example : MKSA(8.175_cm/s) returns .08175_m/s Too, see ... http://en.hpprime.club/docs/reference/MKSA For your example for added, in °F, (see image). Kind Regards. informach. 

05042016, 08:56 PM
Post: #3




RE: units anomily
Thanks for the reply informach,
I would have expected something as simple as units conversion to be easier than that on the Prime. road 

05052016, 03:10 AM
(This post was last modified: 05052016 03:19 AM by compsystems.)
Post: #4




RE: units anomily
Hi, the following code is compiled successfully, but not run in HOME MODE. why?
Code:
CAS MODE VIEW test() [ENTER] 10_°F HOME MODE VIEW test() [ENTER] program({},{},{RETURN 10_(°F)}) ??  Because when you enter the function [VAR] [CAS] does not automatically add the parentheses? test [ENTER] (NULL)>BEGIN RETURN(5_(°F)+5_(°F)); END; default should automatically place the brackets, otherwise placed on the history the program source code =[ test() 

05052016, 05:51 AM
Post: #5




RE: units anomily
Hello
> I would have expected something as simple as units conversion to be easier than that on the Prime. Unit conversion are anything BUT simple (unfortunately). The problem of °C and °F set aside, the 'sto' shortcut as in 1_m▶_cm is quite simple and pretty much to the point with very few keystrokes (considering the possibility range of Prime). Now, working with °C and °F, this is a whole other can of worms. °C and °F are not technically units. This is because they are not 0 based. ie, 0°C does not denote the absolute 0 with negative units denoting antiheat. This is where the problem lies. This means that 1°C is not (always) equal to 1°C. If I say: the temperature is 1°C, I mean by that that the temperature is 247K When I say the temperature change is 1°C, I mean that the temperature change is 1K But, the calculator does not get the context. When you tell it to convert 1°C to °F or K, it does not know if the 1°C is the result of a previous subtraction or an 'absolute' temperature. Bernard, in the the CAS has decided that no serious (real life) math/physics calculations will/should use °C and °F, and is basically banning them. It is a defendable position, which makes sense, and which also makes the software developer life much much easier. In home, we recognized that some users would want to do some computation on °C and °F, so we did some extra work to allow, with restrictions, in order to reduce the occurrences of "vitum pillum" (pig latin for "javelot in foot", (sorry I forgot the declination), or, as we would say in modern english: shooting oneself in the foot). But it still fall short of expectations, due to the problem mentioned above, the calculator can not know, when you use 1°C if this is 0 based, or 246°K based. Cyrille Although I work for the HP calculator group, the views and opinions I post here are my own. I do not speak for HP. 

05052016, 01:32 PM
Post: #6




RE: units anomily
(05042016 05:47 PM)roadrunner Wrote: It appears some unit operations are allowed only in CAS while other unit operations are allowed only in Home.Most has been said already by Cyrille. I'd like to add a tiny bit out of the real world: In e.g. refrigeration engineering, where I work, you are required to express differences in Kelvin. No idea how the Prime handles this, but you should be able to add 5K to 5°F. 

05052016, 02:58 PM
(This post was last modified: 05052016 03:05 PM by informach.)
Post: #7




RE: units anomily
Hi!, Thomas Radke:
Today, is impossible, in HP PRIME directly. You must program for allow result. In Wolfram Alpha, you have the conversion (see image). You have a single formula, for create program ... T(°F) = T(K) × 9/5  459.67 Kelvin to Fahrenheit K = 5/9 * (F  32) + 273.15 King Regards. informach. 

05062016, 02:32 AM
Post: #8




RE: units anomily
(05052016 01:32 PM)Thomas Radtke Wrote:(05042016 05:47 PM)roadrunner Wrote: It appears some unit operations are allowed only in CAS while other unit operations are allowed only in Home.Most has been said already by Cyrille. I'd like to add a tiny bit out of the real world: In e.g. refrigeration engineering, where I work, you are required to express differences in Kelvin. No idea how the Prime handles this, but you should be able to add 5K to 5°F. I'm assuming you want a 5K change starting at a temp of 5°F with the final result expressed in °F. To do this, all temp units must first be converted to K so that they have a common zero reference. (CONVERT(5_°F,0_K)+5_K)▶_°F 

05062016, 01:55 PM
Post: #9




RE: units anomily
(05052016 05:51 AM)cyrille de brébisson Wrote: Unit conversion are anything BUT simple (unfortunately) Indeed, when I used the word “simple,” that was my naiveté speaking. About the rest: understandable and reasonable. On a side note, my 48SX thinks 5_°F + 5_°F is 469.67_°F. At least the prime gets that right. road 

05062016, 02:25 PM
Post: #10




RE: units anomily
Hi!, roadrunner:
In Hp48/49/50 series, the convertion's, are incompatible, the K to °F and viceversa. And your example, to 5_°F+5_°F isn't ... 469.67_°F. The correct result, is ... 10_°F Kind Regards. informach. 

05062016, 10:06 PM
Post: #11




RE: units anomily
For the interested, there was a recent thread discussing these issues and possible solutions:
http://www.hpmuseum.org/forum/thread4783.html 

05072016, 05:14 PM
(This post was last modified: 05072016 05:16 PM by Joe Horn.)
Post: #12




RE: units anomily
(05062016 01:55 PM)roadrunner Wrote: On a side note, my 48SX thinks 5_°F + 5_°F is 469.67_°F. At least the prime gets that right. (05062016 02:25 PM)informach Wrote: In Hp48/49/50 series, the convertion's, are incompatible, the K to °F and viceversa. Please note that the logic of temperature arithmetic is different between the 48S/SX and 48G/GX. Roadrunner is correct that the 48SX says that 5_°F + 5_°F is 469.67_°F. The 48G/GX agrees with Informach, saying that 5_°F + 5_°F is 10_°. <0ɸ0> Joe 

05072016, 06:33 PM
(This post was last modified: 05072016 06:38 PM by Paul Berger (Canada).)
Post: #13




RE: units anomily
(05062016 02:25 PM)informach Wrote: Hi!, roadrunner: I can confirm that a 48SX does indeed return 469.67_°F, it would seem that it messes up the units but not in an entirely random manner because 5_°F is 464.67_°R so it would seem that for some reason it converts to °R to make the calculation but does not convert back, 469.67_°R = 10°F It does a similar thing with °C but converts to Kelvin in that case, adding degrees Rankine or Kelvin work as expected. Paul 

05072016, 07:41 PM
Post: #14




RE: units anomily
Paul,
Internally it converts 5_°F to 464.67_°R, then adds 464.67_°R + 464.67_°R to get 929.34_°R then converts 929.34_°R back to 469.67_°F. Once I lost more than a couple points on a homework assignment because of that anomaly. Those were the good ol' days. road 

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