# Python exec() command
**URL:** https://forum.dynamobim.com/t/python-exec-command/23769
**Category:** Uncategorized
**Created:** [July 16, 2018, 7:03am UTC](https://forum.dynamobim.com/t/python-exec-command/23769 "2018-07-16T07:03:18Z")
**Posts on this page:** 11
**Page:** 1
### Author:  [@Peter\_Kompolschek](https://forum.dynamobim.com/u/Peter_Kompolschek)
#### Post date: [July 16, 2018, 7:03am UTC](https://forum.dynamobim.com/t/python-exec-command/23769/1 "2018-07-16T07:03:18Z")
following problem:
i have a string i want to execute like:
string = “2\*A+B”
usually it should work like result = exec string.
when i try that in dynamo i receive only error messages.
any clue?
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### Author:  [@Jonathan.Olesen](https://forum.dynamobim.com/u/Jonathan.Olesen)
#### Post date: [July 16, 2018, 7:06am UTC](https://forum.dynamobim.com/t/python-exec-command/23769/2 "2018-07-16T07:06:26Z")
Please show a screenshot…
Generally you cannot perform math on strings… (Neither in Python nor in Dynamo)
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### Author:  [@Dimitar\_Venkov](https://forum.dynamobim.com/u/Dimitar_Venkov)
#### Post date: [July 16, 2018, 7:18am UTC](https://forum.dynamobim.com/t/python-exec-command/23769/3 "2018-07-16T07:18:48Z")
Posting the error and the code would definitely help. Exec should work fine inside of Dynamo:
You’re possibly trying to reference an argument before assigning it. Maybe having keyword arguments would be easier in that case?
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### Author:  [@Jonathan.Olesen](https://forum.dynamobim.com/u/Jonathan.Olesen)
#### Post date: [July 16, 2018, 7:22am UTC](https://forum.dynamobim.com/t/python-exec-command/23769/4 "2018-07-16T07:22:54Z")
But using strings will give wrong results, at least that’s was what I meant in my original reply 😉
Alternatively you can import the “math” module in Python
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### Author:  [@Peter\_Kompolschek](https://forum.dynamobim.com/u/Peter_Kompolschek)
#### Post date: [July 16, 2018, 7:28am UTC](https://forum.dynamobim.com/t/python-exec-command/23769/5 "2018-07-16T07:28:24Z")
dimitar thank you for your reply.
just found out that it is a problem with dynamo 2+
going back to 1.3 everything is working.
btw code is just the same as your smple 😉
tx peter
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### Author:  [@Peter\_Kompolschek](https://forum.dynamobim.com/u/Peter_Kompolschek)
#### Post date: [July 16, 2018, 7:31am UTC](https://forum.dynamobim.com/t/python-exec-command/23769/6 "2018-07-16T07:31:55Z")
dimitar, asfaik math is not capable of calculating strings… true?
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### Author:  [@Peter\_Kompolschek](https://forum.dynamobim.com/u/Peter_Kompolschek)
#### Post date: [July 16, 2018, 7:54am UTC](https://forum.dynamobim.com/t/python-exec-command/23769/7 "2018-07-16T07:54:46Z")
weird thing it that dynamo doe not calculate but writes output multiple times
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### Author:  [@Jonathan.Olesen](https://forum.dynamobim.com/u/Jonathan.Olesen)
#### Post date: [July 16, 2018, 8:11am UTC](https://forum.dynamobim.com/t/python-exec-command/23769/8 "2018-07-16T08:11:34Z")
It seems that it is repeated the number of times that your formula states?
E.g. “NAF\*2” is repeated twice…
Can you show your entire script and possibly the input from Dynamo if you have that? It would make it easier to understand… 🙂
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### Author:  [@Peter\_Kompolschek](https://forum.dynamobim.com/u/Peter_Kompolschek)
#### Post date: [July 16, 2018, 9:27am UTC](https://forum.dynamobim.com/t/python-exec-command/23769/9 "2018-07-16T09:27:16Z")
Exactly that is the Point ?!
Architekturbüro DI Peter Kompolschek
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### Author:  [@Dimitar\_Venkov](https://forum.dynamobim.com/u/Dimitar_Venkov)
#### Post date: [July 16, 2018, 9:35am UTC](https://forum.dynamobim.com/t/python-exec-command/23769/10 "2018-07-16T09:35:09Z")
If any of your input arguments are strings and you want to use math on them, you’ll first have to convert them to a numeric object. For example:
> A = float(“1.23”)
> B = float(“4.56”)
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### Author:  [@Peter\_Kompolschek](https://forum.dynamobim.com/u/Peter_Kompolschek)
#### Post date: [July 16, 2018, 9:54am UTC](https://forum.dynamobim.com/t/python-exec-command/23769/11 "2018-07-16T09:54:13Z")
dimitar thank you.
thought that even variables shall be string.
by converting them to numbers solved the problem