@pilou said:
Why not increase number of segments of arc circles for have a better precision?
@unknownuser said:
Sketchup gives 2118,27 6442 with circle 1000 segments!
Check my very first post you can make the figure with 75 segs very nicely. I do not subscribe to philosophy more is better. For the OP use one would probably want>=10% etc margin on veneer one buys.
160217.6 ellipse test.skp
@caul said:
@pilou said:
And what is its result in this case ? (Ellipse 400*900)
2118.2799288074484
The result above is for major = 900, minor = 400, if your input refers to the semi axes multiply the result by 2.
This is the correct value irrespective what Op thinks. On-line calculator spits out same number;
In addidition I used two different methods to model ellipse ( 10 x 20 ") to verify the model approach SU uses is ok ( Two circle and parallelogram, plus the one noted above but it is slight mod of parallelogram ) methods;
Attached the result I get for the 400x900 mm ellipse. The actual value is as above and I get 2112.236 => Good enough for me. I get same result if curve is exploded or left as curve. What I did seem to find is welding before scale helps and you have to be very careful to lock axis direction of scale.
bAZ;
Complete integral of second kind required for ellipse;
For drawing Wikipedia best for you. The have an animated approach but call it parallelogram approach, mine almost the same but equal for all practical purposes. Will find link for you https://en.wikipedia.org/wiki/Ellipse
I used online calculator & my length is with .02+% of what they calculate.
I only use 4 points for may drawing then did mirroring to get 1/2. Most of curve was made with Bezier cubic spline Order 3 with seven segments. The scale and my drawing over lay very close.
I think know what problem is but need more test. Think may be adding segments ad infinitinum(sp?)my not be the way one wants to go. As you know SU has two sided faces so deleted duplicate vertices so could see what scale does and raised some questions I want to investigate.
conjuate ellipse.skpBaz: as noted the model was just proof of concept so not worried about segments yet. the 10X5 (semi) " better model reports 24.227n inches for 1/2 , has only 72 edges and looks very nice.
Some way the number I posted above is not correct so forget about running you calculation. BTW that brings up a question. There are several eliptic intergals and the corresponding polynominal curve fits to those. Do you know which type your equation is for.
Attched is pic of ellipse drawn by the means of supplemental chords with no scaling. I included different seg counts just to show what can be done. If there is intersest I'll redo with more care.
Su reports length of 48.364" for size shown.
If you can run the polynomial curve fit equation shown I would appreciate. If this approach is useful for you I'll redo and show how to draw. It is a little more complicated than scaling but not much since you can draw 1/4 and then mirrow.
Oops see one dimension got cropped it is 10"
There is no closed form equation for perimeter of ellipse
it is approximated by p=2PIsqrt[[[ a^2+b^2]/2]^1/2]
The correct value p=4aE where E is the elliptic integral where k=1/asqrt[a^2-b^2]
My limited experience SU primitive geometry contributes as second order impact on processing speed:
Usually its is the graphics processor and computational load of the image textures;
I some times save model and use that, delete all materials and see what the speed a nd program size is;
That at least gives you some idea of the problem facing you. The actions can be done:
You are correct, terrible job on my part trying to explain;
For 32 float, you have 1 sign bit, 8 mantissa bits and 23 significant bits but because way the sign used significant bits is 24. The decimal equivalent digits for 24 bits is 7.2+ digits. Thus you see the basis of the display I was discussing earlier. Using an online converter 0.35 converts to .3499999994039..... and 0.4 to .40000000596046.... and rounding is done for those to read .35...... and .40......... and has nothing to change the precision use internal to the machine. Why the OP machine changes .35 to .40 I can only guess, but if a generic SU issue that would have many more folks flagging the problem so => probably issue with his machine or its operating system. There is zero info provided for it so no further action can be done except by the op.
why ask me when you can go to net do serach on 32 float, look at converter and see what it tells you. The actual precision of 32 bit float is equivalent to about 24 bit when you consider 1 bit sign , 7 bits mantissa. Depending on the mother board you have the actual bus may operate at more than 24 bits and conversion actually happens when the data is stored in memory.
Su 8 runs as 32 bit & does not make any difference what version of windows you use. Think su change to 64 bits at 2014. My 2015 with 64 bits reports as expected. The precision you are changing only effects display precision not any thing to do with internal calculation.
There are on line IEE floating point conversion programs you can run . Float cannot convert all the real numbers exactly so guess is you are seeing a rounding error, that is pain you pay for dynamic range vs accuracy.
BTW the task manager will report what processes are running 32 bits.