octave

问题 I need to get the indexes of all diagonals in a matrix. The matrix can be non square. The diag function gives the values, but I need the coords. So for instance with this: [1 2 3; 4 5 6; 7 8 9] , I want [1 1; 2 2; 3;3] PLUS [2 6] and 3 because they are the upper diagonals of the matrix, and same for below i.e. [4 8] and 7 . So the full list of indexes is: [1 1; 2 2; 3 3], [1 2; 2 3], [1 3], [2 1], [3 2], [3 1] . And I need this in the other diagonal direction too... And it needs to work for

问题 Can anyone explain how the following code: Y(Y==0) = -1 sets all values of 0 to -1. For example for: Y = [1 1 1 0 0 0 1] we get: Y = [1 1 1 -1 -1 -1 1] What is confusing me is that Y==0 does not return a vector of indices. An if I try to use the vector Y==0 directly I get the error: Y([0 0 0 1 1 1 0]) = -1 error: subscript indices must be either positive integers or logicals I would have naturally opted for: Y(find(Y==0)) = -1 and would like to know why the above does not use find TIA 回答1:

问题 I am trying to overload some built-in functions in Octave to perform a custom action prior to calling the built-in version of the overloaded function. In MATLAB (and supposedly Octave), I can do this using the builtin function. The typical function definition would look something like this where I forward all inputs/outputs to/from the built-in after doing my custom action: function varargout = disp(varargin) % Do a custom thing fprintf('Calling overloaded disp!\n') % Now call the builtin

问题 Is it possible in matlab/octave to use the sort function to sort an array based on the relative frequency of their elements? For example the array m= [4,4,4,10,10,10,4,4,5] should result in this array: [5,10,10,10,4,4,4,4,4] 5 is the less frequent element and is on the top while 4 is the most frequent and it's on bottom. Should one use the indices provided by histcount ? 回答1: The following code first calculates how often each element occurs and then uses runLengthDecode to expand the unique

问题 The short story : In the directory ...\octave-4.2.1\share\octave\packages there were initially 45 package subdirectories (with .m and other files), for instance financial-0.5.0 . But I could not find a way to use them . In more detail : I have unzipped the portable (.zip) version of Octave 4.2.1 64 bit for Windows, at 8:00am (useful info for later), into C:\Users\user1\DOCUME~1\apps\OCTAVE~1.1 (originally C:\Users\user1\Documents\apps\octave-4.2.1 ). I have then installed symbolic-2.6.0 (at 8

问题 I have a simple question about randomly generating numbers in Octave/Matlab. How do I randomly generate a (one!) number (that is either 0 or 1)? I could really use an example. Thanx 回答1: Use rand, which generates a uniform pseudo-random number in the range 0..1, and then test this value against a suitable threshold, e.g. 0.5 for equal probability of 1 or 0: r = rand > 0.5 回答2: You should use randi for integer random numbers: randi(2) - 1 回答3: For the sake of variety, here's another way floor

问题 :-) Hi, guys. Is there any way to change the line color and width of function drawRect in Octave ? According to its reference, there's no property-value pair to set in this function. Thanks. 回答1: The drawRect function does not accept a property-value pair, but it does return a graphics handle from where you can set any property: r = drawRect (x, y, w, h); set (r, "color", [1 0 0]); # set to red (RGB triplets) set (r, "linewidth", 5); Use get (r) to see a list of all properties, or read the

问题 I used to have Matlab and loaded all txt-files from directory "C:\folder\" into Matlab with the following code: myFolder = 'C:\folder\'; filepattern = fullfile(myFolder, '*.txt'); files = dir(filepattern); for i=1:length(files) eval(['load ' myFolder,files(i).name ' -ascii']); end If C:\folder\ contains A.txt, B.txt, C.txt, I would then have matrices A, B and C in the workspace. The code doesn't work in octave, maybe because of "fullfile"?. Anyway, with the following code I get matrices with

问题 I have a question with regards to this post: cocktail party algorithm SVD implementation ... in one line of code? I realize there are similar questions to this. However, please note that my particular question takes things in a new direction, inasmuch that I'm looking for a purely Python equivalent. Is this procedure as elegant/simple when written in Python 3.5 (as opposed to the original Octave 'one line of code')? Also include any relevant Python libraries for this kind of application. Of

问题 Hi I am wondering whether anybody can offer any pointers on a potential approach to sizing the bubbles at the water surface (not those below it) in the following image. I would like to use an open source software if possible (my mind is leaning towards octave given that an image is a matrix). I have absolutely no background in image processing so any ideas are welcome. Obviously as a starting point I know the size of each pixel in the raw image (this image is a compressed version) so