# Tagged Questions

Questions on the manipulation of matrices in Mathematica.

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### Derivative of a symbolic matrix

I need to write an elasticity equations as: {{a*∂/∂x,b*∂/∂y},{c*∂/∂x,d*∂/∂y},{e*∂/∂y,f*∂/∂x}}.{{u},{v}} where a,b,...,f are ...
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### Lift and projection method in Least Squares Inverse Eigenvalue Problems [closed]

I need to implement the lift and projection method proposed by XUZHOU CHEN AND MOODY T. CHU in http://www4.ncsu.edu/~mtchu/Research/Papers/lsiep.pdf on page 7 in ...
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### How to speed up filling a matrix as much as possible in a loop?

In order to find the solution of an $n\times n$ system of nonlinear equations by the method $x_{k+1}=x_k-D_k^{-1}f(x_k)$ where $D_k$ is an approximation of the Jacobian and defined by ...
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### LinearSolve on non-square matrices?

I just came across a strange behaviour for LinearSolve (on Mathematica 8.0.0.0). Consider the following definitions: ...
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### Product of $N\ 2 \times 2$ matrices and subsequently solving an equation dependent on the product

I have $N\ 2 \times 2$ matrices, each one containing one variable energy which may be complex. I want to muliply them all together to a single matrix ...
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### Easier way to calculate Taylor remainder in 2nd order series

At the moment I have implemented the code for a Taylor 2nd order series for the function in three variables: $x_3^3+\frac{x_1-x_2}{x_1+x_2}$ The code builds on following expression: ...
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### How to repeat a matrix on it's side?

I have the following matrix in Mathematica: mat = {{0,0,1,1}, {0,1,0,1}} I want to repeat this matrix N number of times on the side. For example if N = 3 then ...
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### sorting eigenvectors of a final combined matrix

I have two matrices m1 and m2 as below: ...
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### errors in simple for loops

Im trying to run the following code, which I have translated from Matlab. I created a for loop nested inside another for loop. mW is a matrix, and ...
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### Output of Coefficientrules into Jacobian matrix

I have a pair of large polynomials in u, v, a1...a9 and b1...b9, generated by ...
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### Enlarge a matrix and fill in zeros [closed]

Suppose I have a dynamically generated 4-dimensional matrix L in the shape shape={d1, d2,d3,d4}, and ...
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### Tolerance of PositiveSemidefiniteMatrixQ [closed]

I believe the following should be True but returns False for me: ...
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### Reliably computing the signature of a matrix with small eigenvalues

When asked to compute the eigenvalues of the following matrix ...