ATAN2 


atan2( dx, dy )
atan2 "2-argument arctangent"
dx a number
dy a number

The atan2(  ) function is used to return the angle of the numbers provided.


An example from the manual shows us how to get and draw the angle between two points using atan2:

X=20 Y=30
FUNCTION _UPDATE()
  IF (BTN(0)) X-=2
  IF (BTN(1)) X+=2
  IF (BTN(2)) Y-=2
  IF (BTN(3)) Y+=2
END

FUNCTION _DRAW()
  CLS()
  CIRCFILL(X,Y,2,14)
  CIRCFILL(64,64,2,7)

  A=ATAN2(X-64, Y-64)
  PRINT("ANGLE: "..A)
  LINE(64,64,
    64+COS(A)*10,
    64+SIN(A)*10,7)
END



We've added some more details to show what is happening here:

angle = atan2( x1-x2, y1-y2 )

Using the angle found with atan2() and combining it with cos(angle) and sin(angle), we are able to draw the line that always points from one point to the other.

Official Manual - ATAN2

437

4 Sep 2023

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