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ATAN2 missing?

PostPosted: Mon Jun 22, 2015 3:26 am
by cdeaglejr
The ATAN2 function appears to missing.

a = 0.5

b = -0.765

c = atan2(a, b)

PRINT "c = ", c

END

Start program
No such variable line # 5

Re: ATAN2 missing?

PostPosted: Wed Jun 24, 2015 12:40 am
by Andries Pretorius
Agree. I've got Control BASIC v0.79. Gives the same error!

Re: ATAN2 missing?

PostPosted: Wed Jun 24, 2015 3:16 am
by Andries Pretorius
ATAN2 was first implemented in the Control BASIC v0.75 firmware.

I therefore tested ATAN2 with the following firmware versions:
Control BASIC v0.75
Control BASIC v0.76
Control BASIC v0.77
Control BASIC v0.78
Control BASIC v0.79
Control BASIC v0.80

I can confirm that ATAN2 ONLY works in the Control BASIC v0.75 firmware and NONE of the subsequent firmware versions up to v0.80.

Maybe Daniel can help here!

Regards

Andries Pretorius

Re: ATAN2 missing?

PostPosted: Wed Jun 24, 2015 5:31 am
by cdeaglejr
Here's a four quadrant inverse tangent subroutine named ATAN3. It determines angles between 0 and 2 PI radians.

Code: Select all

' demo_atan3.bas

' June 24, 2015

' demonstrates how to intereact with the ATAN3 subroutine

dtr = PI / 180.0

rtd = 180.0 / PI

angle_deg = 222.25678

' convert angle to radians

angle_rad = dtr * angle_deg

' compute sin and cosine of angle

a = sin(angle_rad)

b = cos(angle_rad)

' call four quadrant inverse tangent

GOSUB ATAN3:

' print results

print " "
print "user-defined angle = ", angle_deg, " degrees"
print " "
print "a = ", a
print "b = ", b
print " "
print "angle from ATAN3   = ", rtd * c, " degrees"

END

ATAN3:

  ' four quadrant inverse tangent function

  ' input

  '  a = sine of angle
  '  b = cosine of angle

  ' output

  '  c = angle (0 =< c <= 2 * pi : radians)

  '''''''''''''''''''''''''''''''''''''''''

  pidiv2 = PI / 2.0

  x = a

  GOSUB SIGN:

  sgn_a = sgn

  x = b

  GOSUB SIGN:

  sgn_b = sgn

  IF (ABS(a) < 1.0e-10) THEN

    c = (1.0 - sgn_b) * pidiv2

    RETURN

  ELSE

    c = (2.0 - sgn_a) * pidiv2

  ENDIF

  IF (ABS(b) < 1.0e-10) THEN

    RETURN

  ELSE

    c = c + sgn_a * sgn_b * (ABS(ATAN(a / b)) - pidiv2)

  ENDIF

RETURN

'''''''''''''''
'''''''''''''''

SIGN:

' sign of a variable subroutine

' input

'  x = argument

' output

'  sgn = sign of x

''''''''''''''''''

IF (x > 0.0) THEN

   sgn = 1.0

ENDIF

IF (abs(x) <= 1.0e-12) THEN

   sgn = 0.0

ENDIF

IF (x < 0.0) THEN
 
   sgn = -1.0

ENDIF

RETURN



Here are the results from the demo;

Start program

user-defined angle = 222.25678 degrees

a = -0.672454395
b = -0.7401385589

angle from ATAN3 = 222.25678 degrees

Program Ended.