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### about using math

Posted: **Wed Jan 31, 2018 10:16 am**

by **tinhaode**

hello!

I would like to use some of math related function calls like pow, sin, sqrt...

But it seems math function doesn't work with SDK.

Either #include<math.h> on user_main or -lm on the Linker doesn't work too.

Do you have any idea to work them out?

### Re: about using math

Posted: **Thu Feb 01, 2018 8:20 am**

by **AgentSmithers**

That's funny. I was just reading this today.

http://moishelettvin.blogspot.com/2005/ ... posed.htmlIndirectly it may relate to your question.

### Re: about using math

Posted: **Mon Feb 05, 2018 9:11 am**

by **tinhaode**

sorry I can't open the url. could you copy some word?

### Re: about using math

Posted: **Fri Feb 09, 2018 12:37 am**

by **AgentSmithers**

tinhaode wrote:sorry I can't open the url. could you copy some word?

What math functions would you like, How fast do they need to be?

Functions like Sin I think is 1 = x^2 + y^2 so I think if you take an argument you just do 1 - (arg)^2 = Value then SquareRoot that I think. Sorry I took trig like a year ago and it's already gone XD

### Re: about using math

Posted: **Sat Mar 24, 2018 1:02 am**

by **Pato**

Hey,

@AgentSmithers: Indeed a kind of last resort solution would be to re-write the math functions (e.g. with Taylors series approximations, it's in the idea of what you proposed

)

@tinhaode: did you managed to fin a solution ? I'm also trying to experiment with math functions, but I got linker errors. Maybe try using the limirom.a from the RTOS_SDK, it seemed to work for some folks...

https://bbs.espressif.com/viewtopic.php ... math#p3215(failed with same error for me. I use a custom toolchain inspired from esp-open-sdk)

### Re: about using math

Posted: **Tue May 15, 2018 11:59 pm**

by **Pato**

It may help, I was able to link against the math lib after some tweaking:

https://bbs.espressif.com/viewtopic.php?f=7&t=9432

### about using math

Posted: **Fri May 25, 2018 2:12 pm**

by **andreysnug**

You could use GetAsyncKeyState from windows.h to detect key presses and program your own macros using SendInput.

### Re: about using math

Posted: **Mon Oct 05, 2020 5:52 pm**

by **neilwalker**

**MCian wrote:**Could you please explain more about GetAsyncKeyState? Can I use nodemcu-build for the ESP8266 WiFi SOC? I'm a student from Meycauayan College and I'm doing a project and need to use a math library

buyessays tasks.

Full math library on nodemcu-build.com >>

github.com/nodemcu/nodemcu-firmware/issues/2403

As for the GetAsyncKeyState function, here it is described:

docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getasynckeystate