Rank: 970 based on 111 downloads (last 30 days) and 2 files submitted
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H.J. Sommer

E-mail
Company/University
Penn State University
Lat/Long
40.8081016540527, 77.921501159668

Personal Profile:

Joe Sommer specializes in 3D kinematics, mechatronics and biomechanics with research ranging from laser vibrometry, to video inspection, to osteometric statistics, to locomotion in microgravity, to tractor overturn. See http://www.mne.psu.edu/sommer

Professional Interests:
kinematics, dynamics of machinery, mechatronics, biomechanics

 

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Files Posted by H.J. View all
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30 Nov 2008 Screenshot polygeom.m POLYGEOM computes area, centroid location, area moments of inertia and perimeter of closed polygons. Author: H.J. Sommer area, centroid location, area moments, inertia, polygon 89 13
  • 4.84615
4.8 | 13 ratings
15 Oct 2008 Screenshot Fit logarithmic spiral to x,y data Fits logarithmic sprial r=a*exp(b*theta) to x,y data points. Author: H.J. Sommer fit, curve, logarithmic, spiral, log 22 0
Comments and Ratings on H.J.'s Files View all
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29 Jan 2013 polygeom.m POLYGEOM computes area, centroid location, area moments of inertia and perimeter of closed polygons. Author: H.J. Sommer charlie

Excellent program.

Question: Is J = Iuu + Ivv valid only for circular cross sections?

01 Oct 2011 polygeom.m POLYGEOM computes area, centroid location, area moments of inertia and perimeter of closed polygons. Author: H.J. Sommer Tweddell, Steve

Excellent function, a real time saver

14 Apr 2011 polygeom.m POLYGEOM computes area, centroid location, area moments of inertia and perimeter of closed polygons. Author: H.J. Sommer Crozier, Richard

14 Apr 2011 polygeom.m POLYGEOM computes area, centroid location, area moments of inertia and perimeter of closed polygons. Author: H.J. Sommer Crozier, Richard

Raghuram, the correct answer is given if you reorder your vertices so they are given clockwise around the outside of the polygon, rather than just specified randomly, e.g,

% Your vertices
% x = [1.0000 0.5000 0.8333 0.5694];
% y = [1.0000 0.1667 0.5000 0.5694] ;

% reordered moving clockwise around the polygon from (0.5, 0.1667)

xy = [0.5, 0.1667;
0.8333, 0.5;
1, 1;
0.5694, 0.5694; ];

x = xy(:,1);
y = xy(:,2);

for i = 1:numel(x)-1
line(x(i:i+1), y(i:i+1), [0,0], 'Color', 'b');
hold on
end

line([x(end), x(1)], [y(end), y(1)], [0,0], 'Color', 'b');

[ geom, iner, cpmo ] = polygeom( x, y )

plot(geom(2), geom(3), '+r')

hold off

23 Feb 2011 polygeom.m POLYGEOM computes area, centroid location, area moments of inertia and perimeter of closed polygons. Author: H.J. Sommer Raghuram

The outputs are erroneous for the following input:
x = [1.0000 0.5000 0.8333 0.5694]
y = [1.0000 0.1667 0.5000 0.5694]
The centroid is computed as (0.8801,1.1496) which is outside the parallelogram formed by the input points.

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