plotAngleDistribution on non uniform ODF

[ThomasChauve]

What do you want to do? I want to compute plotAngleDistribution on an non uniform ODF but it seems that the result is false.

What data do you have? I build ODF using custom function buildODF

What code do you use?

CS = crystalSymmetry('6/mmm', [4.51 4.51 7.34], 'X||a*', 'Y||b', 'Z||c', 'mineral', 'Ice-Ih', 'color', 'light blue');

odf = fibreODF(Miller(0,0,0,1,CS),yvector,'halfwidth',5*degree);

figure;
plotAngleDistribution(odf)

ori=odf.discreteSample(20000);

for i=1:9999
    i
    clc
    mk(i)=angle(ori(i*2),ori(i*2+1));
end

figure;
[counts,centers]=hist(mk);
plot(centers*180/pi,counts,LineWidth=2)
xlim([0,100])

What result do you get I compare a list of angle computed using angle function on 2 orientations obtained using odf.discreteSample to plotAngleDistribution(odf) The results does not match.

What result do you expect That both figures are similar.

Error Message none

Comment

• I have the good behavior when I use an uniform ODF : odf=uniformODF(CS)
• I have other more complex ODF where it does not work either.

What MTEX version do you use? MTEX 5.9.0 Matlab R2021a

I also tried with MTEX 5.8.2 : same result.

[kilir]

Hi Thomas, you are comparing the angle distribution of an odf to the misorientation angle distribution, that's two different things. You probaly should use an mdf.

CS = crystalSymmetry('6/mmm', [4.51 4.51 7.34], 'X||a*', 'Y||b', 'Z||c', 'mineral', 'Ice-Ih', 'color', 'light blue');
odf = fibreODF(Miller(0,0,0,1,CS),yvector,'halfwidth',5*degree);
mdf = calcMDF(odf)

plotAngleDistribution(mdf)

ori=odf.discreteSample(1000);
mk = angle_outer(ori);

% mori=mdf.discreteSample(100000);
% mk = mori.angle;

figure;
[counts,centers]=hist(mk(:),72);
plot(centers*180/pi,counts,LineWidth=2)
xlim([0,100])

Cheers, Rüdiger

[ThomasChauve]

Hi Rüdiger

Thanks for the quick fix. I haven't use MTEX for a while and I didn't recall mdf the last time used it. Therfore I don't really understand what does plotAngleDistribution(odf) . It is just out of curiosity.

Anyway thanks for fix. Best Thomas

[kilir]

Hi Thomas, the angle of an orientation would correspond to the axis-angle representation, the same applies to an odf, which is what plotAngleDistribution(odf) does. Often this makes sense for misorientations but in many cases not really for orientations. Cheers, Rüdiger