# Atan function returns completely incorrect numbers

I am attempting to code my mecanum wheel bot to be able to head any direction. This involves the atan function, as far as I have been able to tell. When I enter two values into the atan function, the numbers returned are completely incorrect. For example, atan(100/-10) should return ~-1.47. VexCode returns -84. As another example, atan(86/81) should give ~0.815. VexCode returns 45. Left and right directions return zero, no matter what. Is there a workaround? Am I doing something wrong? Code is in attachment. When using blocks, the return value of `atan` is in degrees (as the following math shows with the examples that you provided): Example block code: VEXcode’s Blocks-to-Text (python):

``````brain.screen.print(math.atan(15) / math.pi * 180)
``````

As you can see, there is an internal conversion to degrees.

You can invert the math if you want the value in radians (divide by `180/π` or multiply by `π/180`).

3 Likes

That makes sense, thanks. Do you know why the left and right directions return zero? After 45 degrees in either direction, it will switch to zero.

Could you please clarify “left and right directions”? I was probably missing something, but I didn’t quite understand how it relates to the code. The (roughly marked) red sections return zero no matter what

Expected controller points where the return value is 0: If the position of `axis4` is `0`, there may be a `ZeroDivisionError` caused by (you guessed it), dividing by zero. It doesn’t explain why you get 0 anywhere in the range you specified though. I suggest converting to a text project so that you can have a more dynamic output when debugging.

Any errors will show in this panel,

and you can print some test cases there too (such as printing `axis3/axis4` in the while loop).

I got it to return degrees 0-360. It took 111 blocks. Not ideal, but it works.
The joystick also has to be along the edge.

1 Like