friends i am compiling a code that contain this line of code "#include " it fail to compile and had this massage.
"Compilation error: cmath: No such file or directory"
can someone help me how to resolve it
You should post your complete sketch and error report.
If you have a line that reads...
#include<cmath.h>
... you will need to add cmath.h file (and any dependencies) to your "libraries" directory or add cmath.h as a local file/tab in your IDE and change the "<>" to double-quotes...
#include "cmath.h"
Arduino IDE has "math.h" if that helps.
The correct header is <cmath>, not <cmath.h>. It is part of the C++ standard library: Standard library header <cmath> - cppreference.com
This specific error indicates that OP is compiling for an AVR-based board, but the code was intended for a more powerful MCU with standard library support (e.g. ARM or ESP-based boards). If this is the case, replacing <cmath> by <math.h> probably won't help. Either way, more context is needed.
Install the ArduinoSTL library (available in the library manager) and add
#include <ArduinoSTL.h>
before #include <cmath> .