Matlab

Need cross-sectional area of non-convex 3D point cloud.
I've got a 3D point cloud that is not convex, basically representing a cavity. I need to find the cross-sectional area of this point cloud at certain depths, parallel to the x-y plane, such as at z = -1. Conceptually, I've considered using Delaunay triangulation, and then finding where the plane of interest inter... 4 May 2010 17:57

Memory Reallocation broken in R2008b and higher
It was recently pointed out to me by a user of my mtimesx tool that if you start with a large sparse matrix A and then do the operation 0*A, the result takes just as much space as the original A even though it only needs enough space for one element. I tracked it down to the MATLAB API mxRealloc function, and indeed th... 6 May 2010 09:38

InitialMagnification is linear?
I'm fairly sure it's the case but i'd rather ask than to make any assumptions. If an image is too large to be fitted onto your screen MatLab will issue the warning: Warning: Image is too big to fit on screen; displaying at 8% for instance. I'm assuming that the 8% image is a linear "downscaled" version of the or... 4 May 2010 23:31

Relation between Hough & Radon Transform Matrices
Hi! I'm facing a similar problem in matlab with Hough transform . I want to apply the function Hough to my image so that it display me the Hough matrix. Do you know how to achieve? Here's what I've tried: Edges.m contains: %image1 img1 = imread("photo1.jpg" ); % conversion to grayscale img1_grey = ... 4 May 2010 16:48

error ismember with cell arrays
x=find(ismember(A,B)==1 & ismember(C,D)==1); where Name Size Bytes Class Attributes A 31954x1 1442696 cell B 1x1 68 cell C 31954x1 2172872 cell D ... 4 May 2010 17:57

Data Filtering Window
I've taken the Fourier transform of some data and now need to apply a frequency domain filter. I have three sharp peaks and want to isolate one of them with a filtering window. Any suggestions on how I might go about doing this? Thanks! ... 5 May 2010 19:23

Help fixing Gosper curve (image not as it should be)
I have managed to make a little progress with the code i posted earlier, but the image shown is not quite the gosper curve and maybe missign something, ro soem variables are not right. function [X,Y]=Gosper_curve(Lmax) Axiom='XF'; Newx='X+YF++YF-FX--FXFX-YF+'; Newy='-FX+YFYF++YF+FX--FX-Y'; theta=pi/3; alpha=0; ... 4 May 2010 16:48

Problem
My problem is following: I have velocity u and depth z data matrix (1x100). And have to find answer to the du/dz. I know the answer when I have u like a equation - u=2*z+21. But how i manage this problem when I have numerical input data. Thanks ... 13 May 2010 13:48

Relation between Hough & Radon Transform Matrices
Does anyone know the mathematical relationship between the Hough transform matrix, H, and the Radon transform matrix, R? I want to convert R to H so I can use Houghpeaks(...) to find the peaks in the transformed R matrix, assuming it's possible. ... 4 May 2010 16:48

drawing on a matlab figure in guide
Hi, How do you allow the user to draw any shape on a figure in guide? To be clear, say I want to draw a triangle so I want to allow the user to click on 3 points in the figure in guide and I want to extract the points along the perimeter. thanks. ... 4 May 2010 16:48