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David Zhang


Active since 2012

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inqury with the lsim command
I am doing the time-history analysis of structure under earthquake motions. The time step of the recorded motion is 0.001. When ...

10 years ago | 0 answers | 0

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Question


Matrix transform due to reorder of the equation row number, for AX=b
Hi, I'd like to solve equation AX=b, e.g., [a11, a12, a13; a21, a22, a23; a31, a32, a33]*{x1, x2, x3}'={b1,b2,b3}' Howe...

10 years ago | 1 answer | 0

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how to solve non-linear transcendental equation with many roots
Hi All, I have to solve the following equation x-(2*(sinh(x)*((cos(x)).^2+cos(x)-1)+sin(x)*(cosh(x)-1)))/((1-cos(x)*cosh(x...

11 years ago | 3 answers | 0

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how to get the coordinates of Gaussian quadrature point over a triangular
Hi All, I have to integrate over an domain that is discrsized with many tri-angular elements, and i have to take the integr...

12 years ago | 0 answers | 0

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constrained random number generation
Hi All, I like to generate n numbers, a1, a2,...an, which are uniformly distributed, but there are one constraint that sum(a1...

12 years ago | 1 answer | 0

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what is the normalizings in generalized eigvalues in matlab
Hi All, In matlab, i used [V, D]=eig(A, B) then the eigenvectors V can be obtained? but what is the normalizing of V...

12 years ago | 1 answer | 0

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Question


How to numerically integrate bessely function
Hi All, i want to get the integral result for bessely function as int{a}{b}int{a}{b}bessely(1, x1-x2)dx1dx2 but when num...

12 years ago | 0 answers | 0

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answers

Question


why tensor product of Gaussian quadrature point cannot reach exact integration result
Hi All, I have to numerically evaluate a double integration as int_{a}^{b}int_{a}^{b}c(x, y)f(x)f(y)dxdy I used the Gauss q...

12 years ago | 1 answer | 0

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Question


how to create matrix using vectors
Hi All, my problems is how to create matrix Aij{n by n} using vector Bi{1 by n} and Cj{1 by n}, where Aij=f(Bi, Cj). I dont li...

12 years ago | 1 answer | 0

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how to create a surf plot for {x, y, z} where z is also a vector, thanks all!
Hi all, my problems are This is a simple mesh with four points 1,2 3 and 4, whose coordination are (x1, y1),...,(x4, y4), now i...

12 years ago | 1 answer | 0

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Question


how to generate a vector of uncorrelated random varaibles
Hi all, I like to generate a vector of uncorrelated random variables in matlab? is anyone have some suggestion to me? Thanks

12 years ago | 1 answer | 1

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Question


why dblquad can not be used to evaluate the bessel function of the second kind bessely
Hi All, I like to calculate the double integral of Bessel function as clear clc a=0; b=2; syms x y A= db...

12 years ago | 2 answers | 0

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Question


how to make the inline function can identify the matab coded function
I am using the sybolic toolbox of matlab but find the inline function cant identify the matlab coded function. For example, i...

12 years ago | 1 answer | 0

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