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calculating trace of matrix without calculating the matrix itself
Let tmp be an n by n matrix. B = tmp(vecx+n*(vecy-1)).'; (Note: The ‘trace’ is the sum of the diagonal elements of A, no...

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Subscripted assignment dimension mismatch
’temperature' is an array, not a scalar, and when the scalar 'matrice_cartesian(i,10)' is subtracted from it, it remains an arra...

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Sample from multivariate exponential distribution
You can make use of the ‘gammaincinv’ function for this problem: X = randn(m,n); X = X.*repmat(gammaincinv(rand(m,1),n...

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hey guys.,x1=[6.630]; y1=[12.294]; z1=[-1.457]; x2=[7.613]; y2=[12.686]; z2=[-0.404]; x3=[8.324]; y3=[11.427]; z3=[0.102]; x4=[9.372]; y4=[11.018]; z4=[-0.564]; these are coordinates to calculate phi and psi angles, please tell me how i should do.?
(Corrected) I am assuming that the four sets of coordinates you describe correspond to four points P1 = [x1;y1;z1], P2 = [x2;y2;...

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MVNRND in PC vs. MAC
It is likely that very small differences in the computations that produced your ‘sigma’ matrix are the cause of the differences ...

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How can I write such an equation on Matlab?
Recursion is not a good idea on an iteration of this sort where at each step two different earlier levels are consulted. At the...

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Draw the curve in the x–y plane for which ||(x; y)||inf = 2
plot([-2,2,2,-2,-2],[-2,-2,2,2,-2],’y-‘)

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How to store the results from an iteration process?
You have one too many for-loops clear all A = (1:10)'; x = [5,11]; for i = 1:2 C(:,i) = A * x(i); end ...

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how to define an ellipse using a tangent line and point ?
Arbitrary ellipses in a given two-dimensional plane enjoy five degrees of freedom - that is to say, in a sense they occupy a fiv...

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Warning: Explicit solution could not be found. In solve at 81 ans = [ empty sym ]
By a certain trick my ancient version of ‘solve’ can find the solution to your problem which involves the ‘lambertw’ function. ...

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Find length of intersection between 2 points and a sphere
Since this problem is in three dimensions, you can also make use of the cross product function to compute L as follows. Again, ...

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how can i calculate a equation including exceeding value of realmax
It is essential that you include the exp(-lambda), which is part of the Poisson distribution, in your calculations. p(x,lam...

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Find length of intersection between 2 points and a sphere
Let P1 = [x1,y1,z1], P2 = [x2,y2,z2], and P0 the sphere center. v = P1-P0-dot(P1-P0,P2-P1)/dot(P2-P1,P2-P1)*(P2-P1); L =...

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How to remove zero sum row from matrix
A = A(:,(A(2,:)+A(3,:)~=0));

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how to convert u(r,z) (axisymmetric) data to u(x,y,z)??
Probably I don't understand your question, but it would seem that the following is the obvious answer, where uppercase 'U' is th...

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Vectorizing the creation of an (m x n) matrix where each row represents a number
Assuming y is a column vector yk = zeros(m,n); yk((1:m)’+m*(y-1)) = 1;

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How to solve DE by matlab
I can help you a little in finding the analytic solution. Temporarily consider that y is the independent variable and t is the ...

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Plot a Surface on a circle and annulus
For the circle (disk) do this: [T,R] = meshgrid(linspace(0,2*pi,64),linspace(0,2,16)); X = R.*cos(T); Y = R.*sin(T); ...

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how to add combinatorics function in matlab with n different objects divided into r groups and each group get at least 1 object
C = zeros(r^n,n); t = 0; for k = 0:(r^n)-1 s = dec2base(k,r,n); if length(unique(s))==r t = t+1; ...

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How do I select values bigger than a certain value & at least 4?
Let A be your 2500 by 1 row vector. f = find(diff([false;A>150;false])); f1 = f(1:2:end-1); ix = f1(find(f(2:2:end)-f...

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How can I solve this problem?
In “ _observe a relationship recurrence between two successive terms, Ti+1 and T1_ ” I believe you are being asked how the n+1-s...

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Solving an Integro-differential equation numerically
I hate to see numerical approximation methods used when there exists a very simple and precise method done by hand. First we de...

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how to do sum up elements one by one (sequence addition)
cumsum([1 2 3 4]) equals [1 3 6 10]

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How many combination will appear
I hope you have a lot of memory available to matlab! B will be of size 85900584 by 7. That is, there will be 49!/7!/42! combin...

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How to put data in vector into matrix
The following is an example of inserting a row vector, V, into an m by n matrix, M, in a “spiral transposition”. The spiral in ...

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I would like to know how I can have the line of a matrix.
By “line” I assume you mean “row”. If you know the row in A that has its maximum, that is the same row as the one in P that wou...

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How may I use the find function to search a range or rows and a specific column please?
The 'B' values are the column indices of the matrix X(1:3,4), and relative to this matrix those column numbers are all ones.

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How to calculate the area between the curves y=1/x and x-axis from 3 to inf
Such an area would be infinite-valued. You have to find the integral of 1/x with respect to x from 3 to infinity, and that give...

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Create and plot random points with connected lines
Assume that A is symmetric with zeros on the diagonal (bidirectional connections) and that there are n points. x = rand(n,1...

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Non-linear Implicit function plot
You could plot it using a third variable, t: n = 200; t = linspace(-2,2,n); % <-- Choose appropriate range for t for ...

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