Recent content by azizz

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    Solving Problem Involving Cross Product

    Sorry about that. Its more than obvious that it is impossible to solve the problem as I stated it before. Let me give you some more information about my issue. And what I want to do. Perhaps that will make it more clear. Suppose we have a wig with a centre of gravity x and a rotating point o...
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    Solving Problem Involving Cross Product

    Hey, I have a problem that can be written in the following form: u=v x w where u, v, w are 3by1 vectors and x is the cross product. now I want to write v in term of u and w, but I have no idea of how to get vector v out of the previous equation. Someone who can help me with this...
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    3 equations, 3 variables: can it be solved?

    That works indeed. Thanks a lot!
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    3 equations, 3 variables: can it be solved?

    For a kinematic problem I obtained the following equations: p1=- r*sin(theta_c) - d*cos(psi_a)*sin(theta_a)+c1 p2=d*sin(psi_a)*sin(theta_a)+c2 p3=d*cos(theta_a) + r*cos(theta_c)+c3 I want to solve these equations for theta_a, psi_a, theta_c, assuming that all other variables are known...
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    Refreshing gear ratio and total inertia

    Suppose we've got the setup as shown in the figure (see attachment). The idea is that the motor transfers its speed and force (rotary) to the actuator force and speed (linear) via some gears and a spindle. Here: R = radius [m] J = inertia [kg m^2] n = rotary to linear transmission [---]...
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    "Proof of Sum of Eigenvalues Inequality

    Ok thanks a lot for your time! It really helped me.
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    "Proof of Sum of Eigenvalues Inequality

    So if I understand it correctly I can say that \lambda_{\max} (A) + \lambda_{\max} (B) \geq \lambda_{\max} (A+B) can be written as \max_{||x_{1}||=1} x_{1}^*Ax_{1} + \max_{||x_{2}||=1} x_{2}^*Ax_{2} \geq \max_{||x_{3}||=1} (x_{3}^*Ax_{3} + x_{3}^*Bx_{3}) The terms on the left hand side...
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    "Proof of Sum of Eigenvalues Inequality

    But if you state it this way, then it seems to me that the inequality holds with equality... For example, if S1 = {1,2} S2 = {2,3} then the set of sums S12 = s1+s2 is equal to S12 = {3,4,5} So if we consider max(S12) and max(S1)+max(S2), then aren't those equal to each other?
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    "Proof of Sum of Eigenvalues Inequality

    Homework Statement Proof: \lambda_{\max}(A+B) \leq \lambda_{\max}(A) + \lambda_{\max}(B) Homework Equations Hint from exercise: \lambda_{\max}(A)=\max_{\|x\|=1} x^*Ax The Attempt at a Solution The problem is that the equation on the left side can not be split. So I tried to...
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    How can I learn about the maximum and eigenvalues of matrices?

    Found partly what I needed: \lambda_{\max}(A)I \geq A \geq \lambda_{\min}(A)I \beta I > A \iff \beta > \lambda_{\max}(A) Now all I have to know is what is known for the eigenvalue of two matrices? That is: \lambda_{\max}(A+B) = ... Is there any expression I can use for such an...
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    How can I learn about the maximum and eigenvalues of matrices?

    Ok, but I think this holds true: Suppose A-B is hermitian and positive definite, then \max_{\|x\|=1} x^*(A-B)x \geq x^*(A-B) x = x^*Ax - x^*Bx \leq \lambda_{\max}(A) - \lambda_{\max}(B)
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    How can I learn about the maximum and eigenvalues of matrices?

    Sorry I went to fast here. With the maximum I meant the largest (or maximal) eigenvalue, for example \lambda_{\max}(A) = \max_{\| x \| =1} x^* A x Then my question is: what do I know of this operator? Is it, eg, linear?
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    How can I learn about the maximum and eigenvalues of matrices?

    Does anybody have a good book/website where I can find good information on how to use the maximum on matrices. I have to prove an expression involving the maximum and eigenvalue of matrices. But I don't know how to link those to together. I think I can figure this out, if only I had some good...
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    Finding Limit of f(i,z) for i_0, z_0

    yes that is right, the limit does not exist. I misused this term. Indeed I am looking for a value for f(i0,z0) such that the function is continuous at this point.
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