Are there built-in math functions that can be used in variable calculations (in basic logic flows, not Homeyscript)? If so, where can I find the docs?
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You can use the Logic-card âCalculate a numeric valueâ in THEN field an set variables to calculated values from other variables or/and tags.
Iâm sorry to say I donât know where you can find the docs.
âYou can even perform math inside a Flow! Surround your formula with curly brackets, for example:
{{ 1 + 2 }}
Of course you can add tags in this calculation.â
This was what I was looking for but I fail to use it.
I tried this in a Simple Logic card:
{{print('Foo $0', <Temperature>)}}
where is one of the Tags I get the following on the timeline:
{{print('Foo $0', 19.9)}}
where 19.9 is the value of
What am I doing wrong?
What do you expect of the âprintâ function?
I expected Foo 19.9. I assumed it was like sprintf in C.
When I tried {{ 10 + 20 }} it returned 30.
When I looked at the link https://mathjs.org/docs/reference/functions.html above I assumed all functioned were possible to use. Maybe it was wrong assumption.
Iâm not sure, but I expect print means print to terminal, what not is possible at Homey
The math.print() âvaluesâ argument (the second one) is expected to be an object, an array or a matrix, not a scalar value.
Try this:
{{ print('Foo $0', [ <Temperature> ]) }}
When I enter your proposal I get the following:
{{ print('Foo $0', [ 19.9 ])}}
which is the same as I got earlier.
It seems like I fail with the print function. But I do realize how to solve my initial problem which was to create a string including a tag value in the middle. I wanted to create a json string, e.g. {{ value : <Temperature> }}.
I thought I needed the print function for it nut it now works with what you just gave me above. Thanks!
are spaces allowed?
floor(x) : partie entiÚre mathématique usuelle = entier immédiatement inférieur à x
ceil(x) : partie entiÚre par excÚs = entier immédiatement supérieur à x
round(x) : arrondi entier le plus proche
abs(x) : retourne la valeur positive
sqrt(x) : racine carrée
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English please.
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Hi, I am working on some logic for circadian lighting. I want to use a calculation {{(85-âlight percentageâ)/100}} to set a light temperature variable between 0 and 85 based on the light percentage (provided by sun events). But I want to prevent the results from becoming below zero. Any ideas on how to do this? The reason I use 85 as base is because I donât want the temperature higher than 85 in the evening (2000K).
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max(CALCULATION, 0)
Ah of course! I misunderstood the function of min() and max() at first! Used your logic but applied to the min() formula. This prevents negatives as wel and also ensures it is 0.85 at most.
{{Min(((100-âLight percentageâ)/100),0.85)}} is the result and it works amazing!!
Thanks for your insight 
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Some more inspiration. I used this calculation in standard homey variable calculation to convert a number (in string format from MQTT) to valid dim-value for a homey dimmer:
{{round(number(<variable/tag)/254,2)}}
Where <variable/tag> is the variable or tag with string that you want to convert. In this case a value between 0-254 that converts to 0-1 with 2 decimals.
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I also would like to round the result of a formula with a tag in it, doesnât workâŠ
What I have, this works :
{{ ( Prijs nu + 0 + 0.0023 + 0.13979 ) * 1.06 }} â returns something like 0.4869534 (would like it to return 0.49)
(where âPrijs nuâ is a tag coming from the âPower by the hourâ app.
What Iâm trying :
{{ round ( ( Prijs nu + 0 + 0.0023 + 0.13979 ) * 1.06 ),2 }} â returns empty var
Also, following your example :
{{ round ( ( number (Prijs nu) + 0 + 0.0023 + 0.13979 ) * 1.06 ),2 }} â returns empty var
Where is my logical error�
If this works:
{{ ( Prijs nu + 0 + 0.0023 + 0.13979 ) * 1.06 }}
It should work with round like this:
{{ round ((( Prijs nu + 0 + 0.0023 + 0.13979 ) * 1.06) ,2) }}
Or this as well:
{{ round (( Prijs nu + 0 + 0.0023 + 0.13979 ) * 1.06 ,2) }}
Keep the closing ) in mind:
round(value,x)
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