@tig said:

Why not use 90.degrees etc and return the angle.radians to see what it is in degrees too... skip all of the PI and radian confusion...

=====> I tested with 90.degrees, but I thought it was the conversion that was bad

Why are you making your axe/up vectors so complex ?
Your figures are off too...
axe = Geom::Vector3d.new(-0.999782867743517, -0.0208378829670674, 0.0)

=====> because it is real vectors returned with axe.inspect
I was given a real example.

Which is a very tiny number that's ALMOST zero

This is a a simple tolerance issue...

======>Tolerance has importance here because it is cumulative.

BUT to test for tiny values use something like:

a 'rounding' method - here to 6dp.

angle=(angle*106).round.to_f/106
angle==0
true

This will then trap for these tiny inaccuracies...

...

thank's Dan Rathbun

i have sketchup 8 !!!

it's not angle between, but the subtraction.
because the calculation of the angle is good.

Hi all,

I have a strange result when I subtract two angle in radians!!!!

example :

<span class="syntaxdefault">axe </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> Geom</span><span class="syntaxkeyword">;;</span><span class="syntaxdefault">Vector3d</span><span class="syntaxkeyword">.new(-</span><span class="syntaxdefault">0.999782867743517</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">-</span><span class="syntaxdefault">0.0208378829670674</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> 0.0</span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault">up </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> Geom</span><span class="syntaxkeyword">;;</span><span class="syntaxdefault">Vector3d</span><span class="syntaxkeyword">.new(</span><span class="syntaxdefault">0.00335712544250249</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">-</span><span class="syntaxdefault">0.161071856847676</span><span class="syntaxkeyword">,</span><span class="syntaxdefault"> 0.98693697196954</span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault">axe</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">normalize</span><span class="syntaxkeyword">!<br /></span><span class="syntaxdefault">up</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">normalize</span><span class="syntaxkeyword">!<br /></span><span class="syntaxcomment"># (90 deg) = 1.5707963267948966 in rad<br />#(Math;;PI/2.0) = 90.0 in degrees, 1.5707963267949 in radians<br /><br /># angle between up-axe = 90.0 in degrees, 1.5707963267949 in radians<br /></span><span class="syntaxdefault">angle </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">(</span><span class="syntaxdefault">Math</span><span class="syntaxkeyword">;;</span><span class="syntaxdefault">PI</span><span class="syntaxkeyword">/</span><span class="syntaxdefault">2.0</span><span class="syntaxkeyword">)</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">+</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">(</span><span class="syntaxdefault">up</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">angle_between axe</span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault">puts angle</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">radians  </span><span class="syntaxcomment">#=> 180 degrees, 3.14159265358979 radians GOOD !!!<br /><br /></span><span class="syntaxdefault">angle </span><span class="syntaxkeyword">=</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">(</span><span class="syntaxdefault">Math</span><span class="syntaxkeyword">;;</span><span class="syntaxdefault">PI</span><span class="syntaxkeyword">/</span><span class="syntaxdefault">2.0</span><span class="syntaxkeyword">)</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">-</span><span class="syntaxdefault"> </span><span class="syntaxkeyword">(</span><span class="syntaxdefault">up</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">angle_between axe</span><span class="syntaxkeyword">)<br /></span><span class="syntaxdefault">puts angle</span><span class="syntaxkeyword">.</span><span class="syntaxdefault">radians  </span><span class="syntaxcomment">#=> 1.27222187258541e-014 BAD,  2.22044604925031e-016 in radians BAD &nbsp;</span><span class="syntaxdefault"></span>

can you help me ?

@tig said:

I do not know this tool in any detail... but in passing... I see that there are $ global variables like '$preview' these are dangerous - especially if they have simplistic names [like 'preview'] as other authors might have used them [ill-advisedly] too, as globals works across all scripts in that session - better to use '@preview' as an instance variable, or '@@preview' as a class variable, to hold your data specifically for your own tool so such potential clashes are avoided...

Yes TIG

when I developed this plugin I had only one months experience the ruby language and API sketchup.
certainly you will find other errors of this type in the source, but I perfecting every day.
in the next release several beginner mistakes are corrected but it will remain.

best regard

@jim said:

@macgile said:

I thought the result would be near to 0 and not of 4.

macguile,

4.44089209850063e-016

The e-016 at the end of the number means to move the decimal place 16 places to the left - making the actual number:

0.0000000000000000444089209850063

or very nearly zero. The reason the result is not exactly zero is due to floating point errors as linked above.

thank i nderstand now

regard

@dan rathbun said:

A singleton method to increment a float a, by an argument arg, to dec number of decimal places. (It defaults to 1 decimal place.)

a = 9.0
> def a.incr( arg = 1.0, dec = 1 )
>   dec = dec.to_i
>   arg = round( arg.to_f * 10**dec  )
>   # self is object a
>   temp =( round( self * 10**dec ) + arg ).to_f
>   self =( temp / 10**dec )
> end

use it like:
a = 9.0 b = -1.8 a.incr(b)

THANK for this solution Dan

Best Regard

@voljanko said:

@unknownuser said:

i dont compare anything !!!
i have tested with a = a + b the result is same

I just meant that is always good to avoid considering floats as exact numbers.

oh yes

I thought the result would be near to 0 and not of 4.

@dan rathbun said:

@macgile said:

i have tested with a = a + b the result is same

That is because the Ruby interpreter converts
a += b
to
a = a + b
before the expression is evaluated.

i dont understand your explanation Dan !!!!

@voljanko said:

This is almost zero
It is always a risk when you use floats, in all languages.You should never compare float == float if you don't want problems.

i dont compare anything !!!
i have tested with a = a + b the result is same

hi rallouD

try this : http://pleac.sourceforge.net/pleac_ruby/dbaccess.html