# Available math functions **URL:** \ **Category:** Questions & Help\ **Created:** [August 9, 2019, 9:48am UTC](https://community.homey.app/t/available-math-functions/16622 "2019-08-09T09:48:17Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Diposan](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/diposan/32/46698_2.png) [@Diposan](https://community.homey.app/u/Diposan)\ **Post date:** [August 27, 2022, 9:24am UTC](https://community.homey.app/t/available-math-functions/16622/21 "2022-08-27T09:24:06Z")
Awesome, it works, thanks a lot @Peter_Kawa ! šŸ™ ---
**Author:** ![Juppehup](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/juppehup/32/16748_2.png) [@Juppehup](https://community.homey.app/u/Juppehup)\ **Post date:** [January 26, 2023, 6:10am UTC](https://community.homey.app/t/available-math-functions/16622/22 "2023-01-26T06:10:47Z")
I am trying to get a logarithmic formula to work but it is giving me ā€œError executing expression: Undefined symbol mathā€. I am using ā€œmath.log(10000)ā€ as a test for now, pretty simple, but not working. What am I doing wrong? ---
**Author:** ![robertklep](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/robertklep/32/160628_2.png) [@robertklep](https://community.homey.app/u/robertklep)\ **Post date:** [January 26, 2023, 6:41am UTC](https://community.homey.app/t/available-math-functions/16622/23 "2023-01-26T06:41:21Z")
> [@Juppehup](#): > > What am I doing wrong? Since every function mentioned in this thread doesnā€™t use the `math.` prefix, I would suggest trying `log(10000)` ---
**Author:** ![Juppehup](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/juppehup/32/16748_2.png) [@Juppehup](https://community.homey.app/u/Juppehup)\ **Post date:** [January 26, 2023, 7:01am UTC](https://community.homey.app/t/available-math-functions/16622/24 "2023-01-26T07:01:14Z")
Aaahā€¦it can be so simple sometimesā€¦stupid meā€¦šŸ˜Œ Thanks! ---
**Author:** ![HanZ](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/hanz/32/18371_2.png) [@HanZ](https://community.homey.app/u/HanZ)\ **Post date:** [March 20, 2023, 10:07am UTC](https://community.homey.app/t/available-math-functions/16622/25 "2023-03-20T10:07:44Z")
please give example how you use this in a flow thnx ---
**Author:** ![Tjar](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/tjar/32/61177_2.png) [@Tjar](https://community.homey.app/u/Tjar)\ **Post date:** [July 3, 2023, 9:26am UTC](https://community.homey.app/t/available-math-functions/16622/26 "2023-07-03T09:26:20Z")
Hi Dear readers, Iā€™m also struggling with my first math in advanced flow. I have a flow trigger ā€œon temperature changeā€ and need to transform that value to linear fan control: (temperature - setpoint) \* 5 = level And send that out though MQTT message. The trigger and send out through MQTT works but how can I do the math? The logic block does not accept any input like {{ (temp- 20) \* 5 }} Also: do I need the 'temp" as flow variable or is it possible to inherit the temperature value ā€˜#temperatureā€™ from the previous block for the calculation? ![image](https://us1.discourse-cdn.com/flex025/uploads/athom/original/3X/6/4/649476cf62d7a06fd4421e0e7edc8e3a5c21149b.png) Best regards, ---
**Author:** ![Peter\_Kawa](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/peter_kawa/32/173848_2.png) [@Peter\_Kawa](https://community.homey.app/u/Peter_Kawa)\ **Post date:** [July 3, 2023, 1:39pm UTC](https://community.homey.app/t/available-math-functions/16622/27 "2023-07-03T13:39:15Z")
Hi Tjar, In several cards you can enter the math without needing an ā€˜in-betweenā€™ logic calc card. It seems to work with the MQTT Client card! ![Screenshot from 2023-07-03 15-37-28](https://us1.discourse-cdn.com/flex025/uploads/athom/original/3X/a/6/a657a96228c5e1e4e224a4bf812c631b67de6610.png) . > [@Tjar](#): > > do I need the 'temp" as flow variable or is it possible to inherit the temperature value ā€˜#temperatureā€™ from the previous block for the calculation? Itā€™s the latter (if itā€™s available from the card though). **First connect the two cards (!)** and then you can select the ā€˜inheritedā€™ tag which is on top on the dropdown, under ā€œ_This flow_ā€ When you hover the tag, you can also notice the trigger cardā€™s tag icon gets blue colored, and the card gets a blue shadow. This comes in handy when you have several trigger cards to choose the tag from f.i. ![Screenshot from 2023-07-03 15-40-46](https://us1.discourse-cdn.com/flex025/uploads/athom/original/3X/c/1/c14f3573b841c8b3654f66137987f02b525abdfc.png) ---
**Author:** ![Arie\_J\_Godschalk](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/arie_j_godschalk/32/63027_2.png) [@Arie\_J\_Godschalk](https://community.homey.app/u/Arie_J_Godschalk)\ **Post date:** [July 3, 2023, 10:46pm UTC](https://community.homey.app/t/available-math-functions/16622/28 "2023-07-03T22:46:52Z")
> [@Peter\_Kawa](#): > > In several cards you can enter the math without needing an ā€˜in-betweenā€™ logic calc card. I believe you can use the curly brackets in any textargument. ---
**Author:** ![Peter\_Kawa](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/peter_kawa/32/173848_2.png) [@Peter\_Kawa](https://community.homey.app/u/Peter_Kawa)\ **Post date:** [July 3, 2023, 11:04pm UTC](https://community.homey.app/t/available-math-functions/16622/29 "2023-07-03T23:04:08Z")
Yeah, but while I didnā€™t test all of them, ā€˜severalā€™ would be a safer statement for me to write here šŸ˜… And Homey always seems to have (unexpected) exceptions somewhere šŸ¤Ŗ ---
**Author:** ![HanZ](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/hanz/32/18371_2.png) [@HanZ](https://community.homey.app/u/HanZ)\ **Post date:** [July 4, 2023, 10:44am UTC](https://community.homey.app/t/available-math-functions/16622/30 "2023-07-04T10:44:50Z")
Hi, ik probeer formule te vinden die een getal (#vermogen bv.) vergelijkt of het positief of negatief is, bij positief het getal weergeven indien negatief 0 weergeven. Dit om een variabele te maken die alleen een waarde geeft als de zonnepanelen leveren en 0 weergeeft als het verbruik hoger is als de opbrengst van de zonnepanelen. kan op de site van math.js. org niet mijn gewenste formule deduderen. hoor graag ---
**Author:** ![Peter\_Kawa](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/peter_kawa/32/173848_2.png) [@Peter\_Kawa](https://community.homey.app/u/Peter_Kawa)\ **Post date:** [July 4, 2023, 3:07pm UTC](https://community.homey.app/t/available-math-functions/16622/31 "2023-07-04T15:07:11Z")
Hi Hans, (Mind the topic language šŸ˜‰ ) Edit: found it @HanZ ! ![Screenshot from 2023-07-04 17-39-27](https://us1.discourse-cdn.com/flex025/uploads/athom/original/3X/5/7/579056f559502c5cc2061f99dbaf45553450e816.png) Whoopssā€¦ I got the question wrong at first, but I want to show this function anyways: This is a math way to change negative numbers to positive numbers: ![Screenshot from 2023-07-04 17-04-24](https://us1.discourse-cdn.com/flex025/uploads/athom/original/3X/a/e/ae2e70d9eeb4b711a0d91dae91e704e26934b962.png) ---
**Author:** ![HanZ](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/hanz/32/18371_2.png) [@HanZ](https://community.homey.app/u/HanZ)\ **Post date:** [July 4, 2023, 3:38pm UTC](https://community.homey.app/t/available-math-functions/16622/32 "2023-07-04T15:38:47Z")
Sorry my mistake, thanks Peter, changing a negative outcome to a positive outcome = multiply by -1 (IMHO) I need to create a variable with a positive outcome or, if the outcome is negative; zero (0) any suggestions on this? ---
**Author:** ![Peter\_Kawa](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/peter_kawa/32/173848_2.png) [@Peter\_Kawa](https://community.homey.app/u/Peter_Kawa)\ **Post date:** [July 4, 2023, 3:43pm UTC](https://community.homey.app/t/available-math-functions/16622/33 "2023-07-04T15:43:20Z")
{{max(0, [YourVar])}} returns a zero when [YourVar] is a negative number, see screenshot in my edited reply above. > [@HanZ](#): > > changing a negative outcome to a positive outcome = multiply by -1 (IMHO) Youā€™re right. I tried this {{[MyNumVar] \* -1}} but that didnā€™t work. This works: {{round([MyNumVar] \* -1)}} But when the value is positive, it also gets changedā€¦ to negative in this caseā€¦ Advantage of using ā€˜absā€™: With math ā€˜absā€™ there is less characters to enter šŸ˜… šŸ¤Ŗ šŸ˜… ---
**Author:** ![Tjar](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/tjar/32/61177_2.png) [@Tjar](https://community.homey.app/u/Tjar)\ **Post date:** [July 7, 2023, 7:01am UTC](https://community.homey.app/t/available-math-functions/16622/34 "2023-07-07T07:01:30Z")
Oh wow, thank you @Peter_Kawa @HanZ maybe uoy can do something like ```auto {{ (value >= reference) true_value : false_value }} ``` So that would become something like: ```auto {{ (value >= 0) value : 0 }} ``` But you could also just return the highest value of two arguments using max() ```auto {{ max(value, 0) }} ``` I havent tried it by the way. ---
**Author:** ![Arie\_J\_Godschalk](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/arie_j_godschalk/32/63027_2.png) [@Arie\_J\_Godschalk](https://community.homey.app/u/Arie_J_Godschalk)\ **Post date:** [July 7, 2023, 8:34pm UTC](https://community.homey.app/t/available-math-functions/16622/35 "2023-07-07T20:34:32Z")
In BetterLogicLibrary you can use way more advanced calculations. Just FYI. ---
**Author:** ![HanZ](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/hanz/32/18371_2.png) [@HanZ](https://community.homey.app/u/HanZ)\ **Post date:** [July 21, 2023, 1:22pm UTC](https://community.homey.app/t/available-math-functions/16622/36 "2023-07-21T13:22:00Z")
Just over the moon I understand (a bit of) the variable things Arie. A topic with a lot of examples and explanations could help (I hoop) ---
**Author:** ![Patrick\_Spadrille](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/patrick_spadrille/32/120160_2.png) [@Patrick\_Spadrille](https://community.homey.app/u/Patrick_Spadrille)\ **Post date:** [March 11, 2025, 7:19am UTC](https://community.homey.app/t/available-math-functions/16622/37 "2025-03-11T07:19:35Z")
I try to do some math inside the card to set a variable to a number. In the number field, i entered {{10+20}} but when i press ENTER, it just delete what i have put in the field. What am i doing wrong? ---
**Author:** ![Peter\_Kawa](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/peter_kawa/32/173848_2.png) [@Peter\_Kawa](https://community.homey.app/u/Peter_Kawa)\ **Post date:** [March 11, 2025, 7:23pm UTC](https://community.homey.app/t/available-math-functions/16622/38 "2025-03-11T19:23:00Z")
Use the ā€œCalculateā€¦ā€ card, not the ā€œSetā€¦ā€ card. ---
**Author:** ![DeBossDK](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/debossdk/32/105832_2.png) [@DeBossDK](https://community.homey.app/u/DeBossDK)\ **Post date:** [April 24, 2025, 8:25am UTC](https://community.homey.app/t/available-math-functions/16622/39 "2025-04-24T08:25:48Z")
Hi all.. A problem I thought would be simple - But nooooo. Iā€™m doing logic drills to inteligently calculate a variable, that Iā€™d use for adjusting a pool-heatpump for tomorrow energy prices. The issue is, that ā€œtomorrow vauluesā€ are not available until around noon today - so the logic canā€™t calculate from 00.00-\>13.00, and the result becomes NaN (or simply empty/NULL when I look at the variable) until prices are available. This does not give an error, but it destroys the following calculations. I canā€™t fint a math function to wrap the calculations, to ensure a number is present. Somethin like a IsNumber() check or similar.. Any ideas? Thanks in advance šŸ™‚ Dennis ---
**Author:** ![Peter\_Kawa](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/peter_kawa/32/173848_2.png) [@Peter\_Kawa](https://community.homey.app/u/Peter_Kawa)\ **Post date:** [April 24, 2025, 2:00pm UTC](https://community.homey.app/t/available-math-functions/16622/40 "2025-04-24T14:00:12Z")
Many Math.js functions will work. [Previous page](https://community.homey.app/t/available-math-functions/16622.md?page=1) [Next page](https://community.homey.app/t/available-math-functions/16622.md?page=3)