Answered
Generating a random binary matrix
Some other suggestions n = 4 ; m = 5 ; A1 = rand(n,m) < 0.5 % a logical array consuming little memory A2 = round(rand...

12 years ago | 0

Answered
An error occurs when setting an axes to current axes.
Most likely, ax2 is empty, because that axes has been deleted … Remove the semi-colon to see if this is indeed the case: a...

12 years ago | 0

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Rearrange 3 small matrices to a bigger one with a certain order: taking first n-rows of each of the smaller matrices after each other
You can use some clever indexing: A1 = cumsum(ones(4,2)), A2 = A1 + 4, A3 = A1 + 8 % as above n = 2 ; % engine ...

12 years ago | 0

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Insert Zeros (m -rows) in an existing Matrix every n-rows in an efficient way
But you *can* use <http://www.mathworks.com/matlabcentral/fileexchange/9984 INSERTROWS>: % data A = cumsum(ones(12,2),1)...

12 years ago | 0

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how to find the length of a directory
The error is most likely to the fact there is variable called dir (or, less likely, length) in your workspace. Try this whi...

12 years ago | 1

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Answered
sorting without moving NaNs
Use a variant of the same trick: A=[6 20; 10 10; 3 NaN; 20 66; 4 NaN; 7 12] B = flipud(sortrows(A,[2 1])) ; % descending...

12 years ago | 0

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Answered
sorting without moving NaNs
A=[20 10 NaN 66 NaN 12] B = sort(A,'descend') A(~isnan(A)) = B(~isnan(B))

12 years ago | 2

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How do I create such matrix ? (please look at the thread for further details)
help cat help vertcat help transpose help reshape After reading about those functions you should be able to do it ...

12 years ago | 0

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Rewriting a value with a loop
VL = bsxfun(@plus,(1:9).',[10 20 30]) % some example data RowsToSelect = [1 3 4 7] VLnew = VL(RowsToSelect,:) ...

12 years ago | 0

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Answered
Error in Matlab - "() Indexing must appear last in an index expression"
size(A,1) (instead of size(A)(1))

12 years ago | 2

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Answered
Limit the state vector
help mod V = [0 1 359 361 -1] V = mod(V,360)

12 years ago | 0

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How do I create such matrix ? (please look at the thread for further details)
So, the original values X4, X5 etc. are not used at all? XYZ = ceil(10*rand(4,6)) % example data RESULT = zeros(size...

12 years ago | 0

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Answered
Running standard deviation on matrix with NaN values
function SD = nanstdrow(X) % NANSTDROW - SD per row ignoring NaNs tf = ~isnan(X) ; % non-nan values X(~tf) = 0 ; % se...

12 years ago | 0

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Answered
For loop for correlation
Here is a method: % create some data A = 10*rand(10,4) ; k0 = 1 ; % reference column % add some columns for demo p...

12 years ago | 2

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Indexing multidimensional matrices using logical arrays
A statement like *_TF = A < 0.5_* produces a logical array TF that has the same size as A. You can directly use TF to index into...

12 years ago | 0

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Answered
How do I create a circulant matrix of shift 3 towards the left ?
It does look like a row-permuted circulant N = 31 ; dn = 3 ; A = eye(dn*N) ; % circulant ix = ones(N,d) ; % m...

12 years ago | 0

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How do I create a circulant matrix of shift 3 towards the left ?
Not very flexible: A = eye(6) A = A([1 4 2 5 3 6],:) % permute as desired A(:,10) = 0 % add some zero columns

12 years ago | 0

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Answered
how can i use multiple expression values in If-then
This should get you started: if A==1 || A == 2 disp('A is 1 or 2') ; end if B == 1 && C == 2 ...

12 years ago | 0

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Cell 2 3d matrix
Use CAT and comma-separated list expansion: sz = [2 3] ; % arbitray size C = {rand(sz), ones(sz), zeros(sz)} % example o...

12 years ago | 0

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how to convert a 2d image of ct scan/ x-rays into 3d model??
Take a look at the various tools in the image processing toolbox. As a starting point: <http://www.mathworks.com/help/matl...

12 years ago | 0

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How to calculate the average without taking zeros values?
No need of a loop: A = [1 2 3 ; 10 0 30 ; 9 0 0] rowMean = sum(A,2) ./ sum(A~=0,2) Note that zeros do not contribute ...

12 years ago | 12

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creating a diagonal matrix?
Like this? q = [10 20 30] ; q = q(floor(1:.5:numel(q)+.5)) % expand (there are many other ways to do this!) dia...

12 years ago | 0

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how to reducing pixel size
A pixel has no dimensions … do you mean to reduce the number of pixels in an image? help imresize

12 years ago | 0

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Undefined function 'findpeaks' for input arguments of type 'double'.
findpeaks is part of the signal processing toolbox in 2013b. Do you have that installed?

12 years ago | 3

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Creating a polyval function
I do not really get your problem, but are you after something like this? x = -5:5 p = [3 2 4] y = p(1) for k=2...

12 years ago | 0

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how to modify a text file replacing an existing string with an user-defined string
fid = fopen('infile.txt','rt') ; X = fread(fid) ; fclose(fid) ; X = char(X.') ; % replace string S1 with strin...

12 years ago | 9

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Answered
split string into 3 letter each
In your loop code, you want to store store a string of three elements into a spot with only 1 element "word(j)". This will not f...

12 years ago | 2

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HELP WITH ESTRACT SUBSTRING OF STRING
If you have version 2013b, there is a function called *strsplit* , that might work on numerical arrays (like strfind used to do)...

12 years ago | 0

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vectorization of for loop
for loops are pretty fast when you use pre-allocation P_new = zeros(32,32) ; for k = 1:32 for l = 1:32 P_ne...

12 years ago | 0

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Why isn't my loop running? (using strcmpi, trying to find a handle for the text)
I don't know why your loop is not running. I suggest you try some debugging. Also you change the array you're looping over insid...

12 years ago | 0

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