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Torsten


Last seen: Today Active since 2013

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Answered
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

Answered
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

Answered
Use of 'ArrayValued' in Matlab numerical integration
f = @(x) 5*ones(size(x)); integral(f,0,2)

1 day ago | 0

Answered
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

Answered
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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Answered
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

Answered
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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Answered
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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Answered
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

Answered
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

Answered
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

Answered
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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Answered
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

Answered
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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Answered
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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Answered
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

Answered
How can i use optimproblem as a free derivatives method?
https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=8736798

3 days ago | 0

Answered
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

Answered
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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Answered
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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Answered
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

Answered
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

Answered
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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Answered
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

Answered
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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Answered
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

Answered
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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Answered
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

Answered
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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Answered
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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