Formatting a float number in rules.

[McMagellan]

To calculate the COP, I would like to display a value with one decimal place. (See $COPIntern in image)

The calculation is 2800 / 460 and it should display 6.1. What should the formula look like?

[stumbaumr]

Without a built-in round()-function this is a rather long piece of coding...

Ups - there is a round() function.

So try $COPRounded = round($COPIntern * 10) / 10;

[McMagellan]

I also tried it with round( ). To demonstrate, I wrote a small test rule to show the problem. The formula is to multiply the internal amperage of the inverter by 230V and add a flat rate of 50 watts for the fan. Then you get the power input of the refrigeration circuit, by which the amount of heat is then divided. This is how I calculate the COP, which should be displayed as a number with only one decimal place.

The test rule carries out the calculation based on your formula with different values ​​for ampere, which is also a decimal number. $BK1COP = round(#Leistung / ((#Ampere * 230) + 50) * 10) / 10; $BK1COP = round(3800 / ((2.0 * 230) + 50) * 10) / 10; Here is the result with different ampere values: (2.0 to 2.7)

A new problem was noticed when parsing the test rule. I use Version Alpha-0776a05, build #537 on Heishamon V4.

ERROR: cannot compute * with a left char value

Here is the test rule. If the last two lines in Timer1 are removed the rule is accepted. The malfunction is reproducible for me.

Round Testrule failed.txt

[stumbaumr]

Adjusted your rule and let it run...

on System#Boot then
  settimer(1,10);
  #Ampere = 2.0;
  #Leistung = 3800;
end

on timer=1 then
  settimer(1,1);
  $COP = round(#Leistung / ((#Ampere * 230) + 50) * 10) / 10;
  #Ampere = #Ampere + 0.1;
end

HeishaMon-round-float-errors.txt

Looks like a float precision error to me... https://stackoverflow.com/questions/76468069/how-do-calculators-handle-floating-point-errors

[stumbaumr]

8 Watts idle, Waterpump energy usage as a function of pump duty, Fan energy usage as a function of rpm and compressor as a function of the compressor current.

And still using an external energy meter and an external heat meter is more accurate...

[McMagellan]

Here is a comparison showing how the Rules round( ) command works when calculating with a decimal number. You can see the course of a real heating cycle.

I will not use the round command for this in the future and am satisfied with the normal result. However, it is critical because, for example, you expect a value of 4.9 for an if command and a value of 4.89999 is returned. Then the if command doesn't work. (if xx == 4.9 then)

This COP display is completely sufficient for me. I would like to have the opportunity to spontaneously view the current COP. It's just a cosmetic mistake not to have a display with only one decimal place.

[github-actions[bot]]

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