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# [HP Prme] Hard time for converting temperature.

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HP Prime
macOS 10.13 High Sierra

I've been trying to convert temperature between the units handled by HP Prime.

The results are:

1) From ˚C to ˚F = wrong conversion or no conversion;

2) from ˚C to  K = no conversion;

3) from ˚F to ˚C = no conversion;

4) from ˚F to ˚R (Rankine) = no conversion;

5) from ˚R to  K = OK;

6) from  K to ˚R = OK;

7) from  K to ˚C = no conversion;

😎 from ˚R to ˚F = no conversion.

Why?

Thank you.

Regards,

Ciro.

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Level 9
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Hi!, @Ciro_Bruno :

For Units, don't use CAS, only use Text.

1) CONVERT(100_°C,1_°F) = 212_°F

2) CONVERT(100_°C,1_K) = 373.15_K

3) CONVERT(212_°F,1_°C) = 100_°C

4) CONVERT(100_°F,1_Rankine) = 559.67_Rankine

7) CONVERT(373.15_K,1_°C) = 100°C

😎 CONVERT(559.67_Rankine, 1_°F) = 100_°F

Kind Regards !.
Have a nice day !.
Provost in HP Spanish Public Forum ... https://h30467.www3.hp.com/
Level 4
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It doesn't sound the problem is there.

Take a look at all those conversions made in CAS mode:

So, I guess it's supposed to work in CAS. And I do need it to work in CAS, since I'm doing fluid mechanics calculations, involving flow energy integrals. The case involves data in a sort of units and I'm counting on HP to help me on that.

It might be a bug or some mistake I've been doing.

Any idea?

Regards,

Ciro.

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Hi!, @Ciro_Bruno :

I try in CAS Mode and too result OK.

The images what you insert in post's i'm not see. Appear, i each image, one yellow triangle with gray border's.

Can you write any example of your problem in fluid mechanics calculations, involving flow energy integrals ?.

Kind Regards !.
Have a nice day !.
Provost in HP Spanish Public Forum ... https://h30467.www3.hp.com/
Level 4
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I've got no trouble in fluid mechanics calculations, except that it doesn't understand that different temperature units are mutually convertible in the same calculation.

That's why I've tried to convert temperature units appart from my calculations. Then I found out that temperatures had an issue for being converted.

So, when solving temperature conversions, I guess all my calculations will be ok.

I could send you the equatons case I had some equation editor. The pictures would be the best way.

Thanks.

Regards,

Ciro.

Level 9
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Hi!, @Ciro_Bruno :

Your examples are solved, with ...

Kind Regards !.
Have a nice day !.
Provost in HP Spanish Public Forum ... https://h30467.www3.hp.com/
Level 8
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Message 7 of 11
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convert(100_(°C),1_(°F))

try

CONVERT(100_(°C),1_(°F))

with "CONVERT" typed in uppercase letters instead of lowercase.  Both work in Home, but only the latter works in CAS.

Note: Both "convert" and "CONVERT" are displayed in uppercase in the CAS history when Textbook Display mode is turned on.  To see what you actually typed, turn Textbook Display mode off (Shift Home Settings, Page 2).

-Joe-
Level 4
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@Joe_Horn wrote:

convert(100_(°C),1_(°F))

try

CONVERT(100_(°C),1_(°F))

Ok, but I've been using CONVERT  in upper case in all those examples. And among all those conversions, the only ones showing troubles are exactly the temperature ones. Take a look at that:

In fact, I haven't myself choosen the upercase. I've typed the value, then the original unit, then "Sto>" and then the unit I wanted to have and ENTER. After that, in the historic, my request became "CONVERT(...". I haven't myself typed the word "CONVERT". The calculator did it.

The temperature conversion hasn't been the issue that brought me to this question. I've been using a very powerfull tool HP has that allows us to type expressions containing units from several unit systems and obtain results with corresponding measures converted to the same unit. At the end, if the answer doesn't match what's desired, just ask to convert to the wanted one and thats all.

This time, dealing with a calculation of power, I've placed a temperature in Rankine at the nominator and a constant which has Kelvin in denominator. The expected behavior was having one of them converted and the answer with both eliminated (same unit in nominator and denominator). Just a matter of dimensional analisys.

However, appart from all other calculations I've been doing this way for more than one year, this one revealed this issue regarding the temperature units. It looks like the calculator doesn't understand that all these units regard the same size (temperature). Probably that's the reason why it hasn't been converting temperature terms inside the same expression.

Considering the next picture, the calculator has been able to simplify the first calculation, but not the second. The first one didn't require conversions.

Although it is supposed to calculate expressions with data given in different units. I've tryed the following expressions just to avoid the command "CONVERT":

It looks like there are some sparse issues regarding other conversions, such as between meter (m) and yard (yd). But temperature conversions are a very critical case:

As I told before, it calculates between Kelvin and Rankine, ˚C and ˚F is quite messy, but other conversions simply doesn't.

I guess we've this might be a bug.

Thanks.

Regards,

Ciro

Level 4
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@Joe_Horn wrote:

convert(100_(°C),1_(°F))

try

CONVERT(100_(°C),1_(°F))

Ok, but I've been using CONVERT  in upper case in all those examples. And among all those conversions, the only ones showing troubles are exactly the temperature ones. Take a look at that:

In fact, I haven't myself choosen the upercase. I've typed the value, then the original unit, then "Sto>" and then the unit I wanted to have and ENTER. After that, in the historic, my request became "CONVERT(...". I haven't myself typed the word "CONVERT". The calculator did it.

The temperature conversion isn't itself the issue that brought me to this question. I've been using a very powerfull tool HP has that allows us to type expressions containing units from several unit systems and obtain results with corresponding measures converted to the same unit. At the end, if the answer doesn't match what's desired, just ask to convert to the wanted one and thats all.

This time, dealing with a calculation of power, I've placed a temperature in Rankine at the nominator and a constant which has Kelvin in denominator. The expected behavior was having one of them converted and the answer with both eliminated (same unit in nominator and denominator). Just a matter of dimensional analisys.

However, appart from all other calculations I've been doing this way for more than one year, this one revealed this issue regarding the temperature units. It looks like the calculator doesn't understand that all these units regard the same size (temperature). Probably that's the reason why it hasn't been converting temperature terms inside the same expression.

Considering the next picture, the calculator has been able to simplify the first calculation, but not the second. The first one didn't require conversions.

Although it is supposed to calculate expressions with data given in different units. I've tryed the following expressions just to avoid the command "CONVERT":

It looks like there are some sparse issues regarding other conversions, such as between meter (m) and yard (yd). But temperature conversions are a very critical case:

As I told before, it calculates between Kelvin and Rankine, ˚C and ˚F is quite messy, but other conversions simply doesn't.

I guess we've this might be a bug.

Thanks.

Regards,

Ciro

Level 8
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Message 10 of 11
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No, this is correct mathematically and by design. You can't use non multiplicative units in caluclations because of the ambiguity of absolute or relative change. Any system which correct handles units will error in mixing of C and F with other units due to the ambiguousness.

Some basic "single back and forth" between C and F are supported, but very limited because there are no ambiguoties possible in that case.

TW

Although I work for the HP calculator group as a head developer of the HP Prime, the views and opinions I post here are my own.
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