How to multiply 2 columns by a scalar number in MATLAB
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Dear All
Hope you all are keeping good.i need 4 columns [X,Y,Z,Volume]in excel and first of all i want to multiply X and Y columns by 0.09 and (Z column contains just one scalar (0.18) value) then want to multiply all these X,Y,Z coordinates to get Volume. the code i am trying is given below. any help is appreciated.
if true
[x, y] = find(handles.maskedImage ~= 0);
% here x and y are created in excel by code line.to calculate the volume. first multiply 0.09 by both columns to get X and Y.
X=times(0.09,x);
Y=times(0.09,y);
Z = repmat(0.18,[length(x),1]);
[FileName,PathName] = uiputfile('*.xls','Save data to spreadsheet');
Volume=times(X,Y,Z);
Data=[X,Y,Z, Volume];
xlswrite([PathName '/' FileName],Data); end
3 Comments
Image Analyst
on 19 Sep 2013
Edited: Image Analyst
on 19 Sep 2013
No it doesn't. Think about what you are doing. Multiplying the x,y coordinates of every pixel in the selected region by the spatial calibration factor does not calculate the volume.
Accepted Answer
Jan
on 19 Sep 2013
X = 0.09 * x;
Y = 0.09 * y;
Volume = X .* Y * 0.18;
3 Comments
Jan
on 20 Sep 2013
@Image Analyst: I'm physicist and therefore very free in the choice of the definition of the term "volume", "pixel" and "coordinates". It could be a sound volume for a generalization of acoustic sound waves in a high-dimensional space with a linear metric. Or the coordinates could have been transformed before by a difference of neighboring elements.
But without doubt you are right and for the standard definition of a spatial volume in the Euclidean 3D space this calculations are not correct.
@Muhammad: You have to check the results with known test data, e.g. a line (Volume==0), a sphere and a rotated cube. I focused on avoiding the failing times().
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