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ode15s and 0de23 very slow at high frequencies
I have no experience with the physical background, but if for low frequencies, the solution somehow looks like sin(0.001*x) and ...

5 years ago | 1

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Answered
Sum of elements of a matrix such that no row or column repeats
p = randperm(n); sum = 0.0; for k = 1:n sum = sum + a(k,p(k)); end where a is the nxn matrix.

5 years ago | 0

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Answered
Index in position 3 exceeds array bounds (must not exceed 1).
You overwrite C when you call contourf.

5 years ago | 0

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Answered
Integrating the results of state space output(ode45)
Alternatively to the solution I suggested previously, you can use Matlab's "cumtrapz".

5 years ago | 0

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potting the integral of a state
If y'(t)=f(t,y) is the state space equation, you get the integral of y by simultaneously solving z'(t)=y(t), z(0)=0.

5 years ago | 0

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How do I write an inductive sequence?
N = 10; % define number of recurrence terms to be calculated x = zeros(N,1); x(1)...

6 years ago | 1

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Answered
substract array elements based on other arrays
setdiff(All,union(R1,R2))

6 years ago | 1

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Answered
Solving large sparse Ax=b with lower bound constraint
Did you try starting from the solution of the unconstraint problem ?

6 years ago | 0

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Answered
dsolve second order differential equation
dySol=diff(ySol,x); dySol(585.8)

6 years ago | 0

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Answered
How to plot graph of value of variable when a parameter is varied
Your equations can only be solved for one value of R, namely R = 0.3 + 0.366*exp(-0.3). This can be seen by dividing equation 1...

6 years ago | 0

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write a function called tri_area returns the area of a triangle with base b and height h
function area = tri_area(b,h) area = 0.5*b*h; end From the command window A = tri_area(3,2)

6 years ago | 4

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Answered
Finite Difference Method to find Steady State
T = zeros(6,5); T(1:6,1) = 10; T(1:6,5) = 50; T(1,2) = 73; T(1,3) = 100; T(1,4) = 85; for n=1:5 for i =2:4 T(n+1,...

6 years ago | 0

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Answered
generate random number from a function that serves as PDF ?
N = 1000; U = rand(N,1); n1 = numel(U(U<=w1)); n2 = N - n1; X1 = sigma1*randn(n1,1); X2 = sigma2*randn(n2,1); X = [X1,X2];...

6 years ago | 0

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How can I randomly extract a element in a vector?
random_element = v(randi(numel(v)))

6 years ago | 0

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Answered
what numerical approach is used for bvpinit?
In bvpinit, the user just specifies a guess on how the solution of the boundary value problem might look. A numerical method i...

6 years ago | 1

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element wise product matrix-vector
Y_t = bsxfun(@times,Y_t,w)

6 years ago | 0

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Unexpected output when trying to plot the solution to a system of nonlinear differential equations
Use hold on between the two plot commands.

6 years ago | 1

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Answered
How do I make a function work with vectors?
tanH = (exp(x)-exp(-x))./(exp(x)+exp(-x))

6 years ago | 0

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How can I put an integral inside a for loop when the bounds depend on the loop's variable?
Phi_ij1 =@(i,j) integral2(@(y,x) B_zi(i,x,y),0,y_min1(j),0,@(y)x_max1(y,j));

6 years ago | 1

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L2 norm of the column
M_norm = normc(M)

6 years ago | 0

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Answered
Curve fitting toolbox - gaussian curve to histogram with no workspace data for the y - value
I think Matlab's "mle" is what you want instead of the curve fitting toolbox.

6 years ago | 0

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lsqnonlin and stretched exponential function
error_bounds = nlparci(x,residual,'jacobian',J) after the call to lsqnonlin. If you don't have a toolbox with nlparci, search ...

6 years ago | 0

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Answered
I'm getting an error related to fmincon
If you mean the eigenvalue largest in magnitude, this should give you a start. Incorporating fmincon can automatize the search ...

6 years ago | 0

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root of nonlinear equation
ft = @( c ) 0.25* ... instead of ft = 0.25* ...

6 years ago | 0

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Answered
stop Ode45 when y is less than a value
As defined, ode45 expects myEvent to have 2 input parameters, but you use 3. Use Opt = odeset('Events',@(t,u)myEvent(t,u,minu)...

6 years ago | 0

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Answered
How to add the value of the 3 highest elements automatically from a vector?
[~,idx]=maxk(y,3); y(idx)=y(idx)+sx; y

6 years ago | 0

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Extracting values that are greater than the threshold
OxygenAlt = Alert(Alert(:,3)>21)

6 years ago | 1

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Fitting to an intergral
Use "ArrayValued=true" as option in the call to integral.

6 years ago | 1

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Answered
Hello guys, I need help.
[X1,X2,X3]=ndgrid(x1,x2,x3); Z=f(X1,X2,X3); %assumes f is vectorized M=[X1,X2,X3,Z]; [~,idx]=sort(M(:,4)); sortedM=M(idx,:...

6 years ago | 0

Answered
Temperature ramp then keep it at constant temperature
Copy the lines where you define the global parameters to the beginning of function "fun" and remove them in the upper part of th...

6 years ago | 1

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