Hello,
I use the Smath units function where and whenever possible, it's fantastic, such a useful check on the formula entered (no missing ^2 etc.).
I don't find temperatures and temperature differences easy but I continue to experiment and practice in order to better understand the rules, certainly praise only, no complaints.

My current difficulty stems from wishing to enter coefficient of thermal expansion values taken from a datasheet in in/in/°F*10^-5 and display in m/m/K*10^-5.
If I use units in/in/°F then the message is "Units don't match".
If I use '1/'°F and modify the unit output to 1/K then I get {'1*'K}/'°F*1/'K, which is the same answer, not metric.
Please, if you have experience using CTE units, I appreciate your assistance.

Regards, Tim

Wrote

I don't find temperatures and temperature differences easy

Attach the document ... units experts will read you, help.

Hi Jean,
Thank you, file attached

CTE_CustomaryToMetric.sm (49 KiB) downloaded 49 time(s).

Wrote

Hello,
I use the Smath units function where and whenever possible, it's fantastic, such a useful check on the formula entered (no missing ^2 etc.).
I don't find temperatures and temperature differences easy but I continue to experiment and practice in order to better understand the rules, certainly praise only, no complaints.

My current difficulty stems from wishing to enter coefficient of thermal expansion values taken from a datasheet in in/in/°F*10^-5 and display in m/m/K*10^-5.
If I use units in/in/°F then the message is "Units don't match".
If I use '1/'°F and modify the unit output to 1/K then I get {'1*'K}/'°F*1/'K, which is the same answer, not metric.
Please, if you have experience using CTE units, I appreciate your assistance.

Regards, Tim

This is a very common question, thus there is a handbook section on this topic.
Option 1: Interactive Handbook > Units > Temperature
Option 2: PDF handbook, section 9.4. It is in German but any translator should help.

section units temperature.sm (33 KiB) downloaded 46 time(s).

... stones don't grow wings [my old friend Richard].

Wrote

Hello,
I use the Smath units function where and whenever possible, it's fantastic, such a useful check on the formula entered (no missing ^2 etc.).
I don't find temperatures and temperature differences easy but I continue to experiment and practice in order to better understand the rules, certainly praise only, no complaints.

My current difficulty stems from wishing to enter coefficient of thermal expansion values taken from a datasheet in in/in/°F*10^-5 and display in m/m/K*10^-5.
If I use units in/in/°F then the message is "Units don't match".
If I use '1/'°F and modify the unit output to 1/K then I get {'1*'K}/'°F*1/'K, which is the same answer, not metric.
Please, if you have experience using CTE units, I appreciate your assistance.

Regards, Tim

Hi. Martin it's wright about the need to use difference temperatures. The expression 90*'°C-20*'°C=-203.15@'°C in your example equals -203.15 Celsius because SMath don't store 90 nor 20 Celsius but store the equivalent values in Kelvins, and further do the difference. For this reason is why you need to use difference temperature units for get the expected value of 70 Celsius.

But in your attached file and what you paste, notice about the " '1 ", this not a numerical one, and appear in blue in SMath. The symbol " '1 " is taken as a new undefined unit, probably for that you get the error about bad units.

Best regards.
Alvaro.