Celsius grade error

[ptc-6026671]

Mathcad Prime Express 3.0:

This is ingenious!!!

Michal Glebowski

[KenFarley]

Looks like a conversion to Kelvin is done prior to the calculation. Or a conversion to some other absolute unit of measure for temperature. All in all, though, kind of disturbing.

[ptc-6026671]

Even if it is converted to Kelvins (it can be as there is no similar problem with Kelvins) I would expect rather value 2 with some noise, not 1... This conversion must be very rough.

[KenFarley]

Why would you expect 2?

275 / 274 = 1.0036...

It might be helpful to know why you're calculating the ratio of two temperatures. Is the ratio being looked for actually the ratio of two temperature changes, i.e. (T2 - T1) / (T4 - T3)? If so, you might have to explicitly make the relation ignore units in order to obtain the expected results.

[ptc-6026671]

Ok, now i see how it's calculated. And why such result appears. As a matter of fact there are some expressions which require dividing temperatures themselves.

I have empirical equation (Yaws) for heat capacity which includes temperature in some powers (Cp=A + BT + CT^2 + DT^3). To obtain value (to be able to process calculation with no units error) I have to divide each T by 1°C. Of course problem is a little more complicated as original expression is in Kelvines so to get each T i have to add 273.15.

[ValeryOchkov]

Better