# \[APP\]\[Pro\] Better Logic Library - Just some better logic, variable and library management

**URL:** <https://community.homey.app/t/app-pro-better-logic-library-just-some-better-logic-variable-and-library-management/5568>\
**Category:** Apps\
**Tags:** app, tools, homey-pro, bll\
**Created:** [December 16, 2018, 10:29pm UTC](https://community.homey.app/t/app-pro-better-logic-library-just-some-better-logic-variable-and-library-management/5568 "2018-12-16T22:29:57Z")\
**Posts on this page:** 1\
**Showing post:** 147

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**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:** [June 25, 2021, 11:35am UTC](https://community.homey.app/t/app-pro-better-logic-library-just-some-better-logic-variable-and-library-management/5568/147 "2021-06-25T11:35:35Z")

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FYI, when using a BL “one of these variables has changed” card, you’ll have to type in the variable names, seperated by a comma. But only variables you created in BL can be used, not the variables provided by an app. Then Homey’s Logics is needed.  
See

> [@DirkG](#):
>
> I used the tags in the card „One of these variables changed“ instead of typing in the name of the variables.

Okay, about the goal you want to reach. I’m guessing you try to catch a changed weather description here?  
I use Openweathermap, and trigger the flow with “The weather has changed”.  
Then, at the AND section, I add a Homey Logic card of the type “text contains”.  
Now select the local variable “weather description” (=weersbeschrijving in Dutch), which is provided by the trigger card. In the web app it can be found under “This Flow” in the selection box.

 ![weatherdescriptionChanged](https://us1.discourse-cdn.com/flex025/uploads/athom/original/3X/3/b/3bdb462e312f4c1c4a200f737af756bade002019.png)  
Now enter f.i. “clear sky” as text.  
You can add 2 more logics cards, with a different weather description of your choice. Make sure to drag the cards down, so “OR” appears between them.

In my example, the notification gets sent when the weather type is “clear sky” or “few clouds” or “whatever weather”.

 ![weatherconditions](https://us1.discourse-cdn.com/flex025/uploads/athom/original/3X/5/5/55b30163fb3c62d442907206e0b7211bb550efac.png)

As you can see in the Timeline notification card, Homey provides for a weather description too (“Beschrijving”), but I can’t find a way to monitor it for changes.

The BL math.js card can be used to calculate with numeric variables  
The equivalent Homey logics card is called “calculate a value”  
Examples:

> [@Available math functions](https://community.homey.app/t/available-math-functions/16622):
>
> 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?

> [@List of available Math.js functions](https://community.homey.app/t/list-of-available-math-js-functions/18665):
>
> Is there a list of math functions that do work? Not all functions listed on [https://mathjs.org/docs/reference/functions.html](https://mathjs.org/docs/reference/functions.html) work. Functions like “{{mean(2, 1, 4, 3)}}” and “{{round(5.345,2)}}” work flawlessly, but but XOR (like {{ xor(8, 2) }}), OR and AND do not seem to work. Or am I missing something? I’m looking for a way to do some bitwise operations in flows. Any help is greatly apprecieated.

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