Error in Float32.spin

John Abshier

I cannot get the Degrees and Radians functions to work.· In the code below they print as zero instead of 45 and 0.785.

CON
  _CLKMODE = XTAL1 + PLL16X
  _XINFREQ = 5_000_000
  c = 180.0 / pi
  d = pi / 180.0
VAR
  
OBJ
    Tv : "TV_Text"
    F : "Float32Full"
    FTS : "FloatString"
PUB Main    | x, y, a, b
  Tv.start(12)                                          ' should check fail
  F.start
  Tv.out($00)                 ' clear
  Tv.out($01)                 ' home
  TV.str(FTS.FloatToString(F.Degrees(0.785))) ' prints 0 not 45
  Tv.out($09)
  Tv.str(FTS.FloatToString(F.Radians(45.0)))  ' prints 0 not 0.785
  Tv.out($09)
  Tv.str(FTS.FloatToString(F.FMul(c, 0.785))) ' prints 44.97719
  Tv.out($09)
  Tv.str(FTS.FloatToString(F.FMul(d, 45.0)))  ' prints 0.785398

John Abshier

Here is the fix

PUB Radians(a) | b, c
  b := a
  c := 0.017453293         ' change
  'sendCmd(FMulCmd + @a) 
  command := FMulCmd + @b
  repeat while command
  return cmdReturn  
PUB Degrees(a) | b, c
  b := a
  c := 57.2957795          ' change
  'sendCmd(FMulCmd + @a) 
  command := FMulCmd + @b
  repeat while command
  return cmdReturn  
 

Paul Baker

Thanks for figuring out a fix John, I was just too busy today to take a look at it.

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

TyreBiter

The same question was asked in thread "Float32.radians seems to fail"
nice to see an answer no matter where it is poster.

camt

Thanks John for posting a fix. I've corrected the problem in both Float32 and Float32Full and sent an update to the object exchange and included the updated library here.

For those interested, this bug was a trap that I'd documented in the Tips and Traps on page 10 of the floating point document - which I then proceeded to fall into myself!

Spin recognizes floating point constants, but all expressions are evaluated as integer expressions unless you use the constant directive.
c := pi / 180.0 ' is incorrect
c := constant(pi / 180.0) ' yields the correct result

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Cam Thompson
Micromega Corporation