# Torsten

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**Content Feed**

How to solve differential equation including derivative of eigenvalue of tensor?

Following Walter's idea, this should give you a start: syms s A = sym('A',[3 3]); % Define characteristic polynomial determi...

8 hours ago | 0

How to plot 4 curves with different constants?

y = @(C,x) (C-x)./(1+x.^2); C = [1 2 3 4].'; x = -2:0.1:2; plot(x,y(C,x))

19 hours ago | 0

Use of 'ArrayValued' in Matlab numerical integration

f = @(x) 5*ones(size(x)); integral(f,0,2)

1 day ago | 0

How to write a code that takes a vector and outputs true if its the same forwards as it is backwards and false if not?

https://de.mathworks.com/help/matlab/ref/flip.html answer = isequal(v,flip(v))

1 day ago | 1

Unable to perform assignment because the size of the left side is 360-by-1 and the size of the right side is 360-by-360.

Elementwise division is required: hip_percent(:,2) = 0.14*asis_d./hip_d + 0.5*(hip_d - asis_d)./hip_d; or simpler hip_percent...

2 days ago | 0

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angle function in matlab formula

It's all written in the MATLAB documentation of "angle": Algorithms angle takes a complex number z = x + iy and uses the atan2...

2 days ago | 1

Using anonymous functions with vectors of unknown number of elements and getting the coefficients associated with the variables

Then n_s = 2; u = randi([-9999, 9999], 1, n_s) c = sym('c',size(u)); kappa = expand((1+u*c.')^2) coefficients = coeffs(ka...

2 days ago | 1

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Nonlinear regression not working

clc; clear all; input0= [160 159 158 157 156 155 154 153 152 151 150 149 148 147 146 145 144 143 142 141 140 139 138 137 136...

2 days ago | 0

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Find close points in two matrices of coordinates

Use "pdist2" to calculate the distances of the sites of the first set to the sites of the second set. Check which rows of the d...

2 days ago | 0

How to fasten the loop

Maybe there are faster commands than arrayfun for extracting the elements of LONG in cell arrays that correspond to sequences of...

2 days ago | 0

Normal random number generation

pd = makedist('Normal'); t = truncate(pd,0,1); r = random(t,1e6,1); figure(1) histogram(r,100) Or directly: r = -sqrt(2)*e...

2 days ago | 1

cumsum function question for integration

cumsum(y_cos*inter_val); is a Riemann sum for the integral of sin(t) - integrated between 0 and x. But the integral of sin(t) ...

3 days ago | 1

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I want to do exponential fitting for power decaying with time

x=[ 65.10 1.0000e+000 65.90 61.0843e-003 70.30 21.3693e-003 ]; fun = @(p)exp(-p*(x(:,1)-65.1)); f...

3 days ago | 0

How to define an ellipse by the eigendecomposition of its transformation matrix?

phi = linspace(0,2*pi,100); S = [1 0;0 4]; xy = S*[cos(phi);sin(phi)]; theta = pi/4; Sxy = [cos(theta) -sin(theta);sin(theta...

3 days ago | 2

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I have some coupled nonlinear ordinary differential equations. Three equations have three 2nd order derivative coupled together. Can someone tell me how I can get the response

Solve the third equation for theta_dotdot and insert this expression in equations (1) and (2). Then use the usual substitution...

3 days ago | 1

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When calling a user defined function, MATLAB throws an error for simple matrix multiplication

"const1" and "const2" are not visible in "planck_function" since you didn't declare them as "global" in the calling program. Bu...

3 days ago | 0

How can i use optimproblem as a free derivatives method?

https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=8736798

3 days ago | 0

how to use symsum for this problem

If you use symbolic variables, you should name them as such. And you shouldn't name a variable "sym", especially if you do symb...

3 days ago | 0

How to code Flux Boundary Conditions for a PDE using ODE15s and method of lines

One of many possibilities: dc/dr = 0 c2 - c1 = 0 -> dc1/dt = dc2/dt De*dc/dr = kf*(C-c) De*(cn-c(n-1))/Vl_stage = kf*(C-...

3 days ago | 0

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Error: Not enough input arguments

r = [2.5 1.2 0.45]; y0 = [1 1 0 1 0 0]; tspan = linspace(0,5); soltrue = ode45(@(t,y)diffun(t,y,r),tspan,y0); yvalstrue = de...

3 days ago | 1

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how to use derivative of function using gradient?

Add the variable "dens_mix" as an algebraic equation to your system (e.g. as y(13)): dydz(13) = y(13) - (partial_dens(1)+partia...

3 days ago | 0

Why fsurf show anything for my function?

Is this an explanation ? clear syms eta__2 zeta__2 Hvs2 =((2305843009213693952*(eta__2 - 8331386150863307/9007199254740992)^...

5 days ago | 0

Curve Fitting Toolbox for Surface Extrapolation

[fitresult, gof] = fit( [xData, yData], zData, ft, opts ); xq = (xData(1)+xData(2))/2; yq = (yData(1)+yData(2))/2; zq = feval...

5 days ago | 0

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dsolve unable to find symbolic solution to sets of ODE

The equations are much too difficult and the size of your ODE system is much too large to be solved symbolically. Use a numeric...

5 days ago | 0

Vectorization: incompatible sizes of arrays

n_p = 3; n_o = 3; P = rand(n_p,2); R = randi(n_p,n_p*n_o,1) IP = (cell2mat(arrayfun(@(i)vertcat(repmat(i,1,n_o)),1:n_p,'Unif...

6 days ago | 0

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how to remove error in the code?

And where is the fiunction "star4" ? Your call should be [t,C] = ode45(@star4, t, C0); % Solve the system according to the tim...

6 days ago | 0

How can I segment a matrix based on the difference between a column's elements of the matrix?

X=[ 8.3700 -53.3090 11.4000 -116.6670 13.0000 -117.8350 26.7000 -105.8580 36.4000 -121.5060 39.40...

6 days ago | 0

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Plot the Planck's Radiation curves Below

x-axis and y-axis for the two plots have very different scales. So there must be an error in your formulae if we compare it to t...

6 days ago | 0

Why is MatLab outputting 0s instead of the value?

E2 = (-1./(1+sec(x)))' instead of E2 = (-1/(1+sec(x)))'

7 days ago | 0

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Any comment to speed up the sum calculation of a function which includes legendre polynomials?

M = 1000; x = linspace(-1,1,M).'; y = x.'; for i = 1:11 Lpix(:,i) = legendreP(i,x); Lpjy(i,:) = legendreP(i,y); en...

7 days ago | 0

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