Answered
Multiply matrix with variables
syms COSFA SINFA COSFR SINFR COSF SINF RA=[COSFA 0 SINFA; 0 1 0; -SINFA 0 COSFA]; RR=[COSFR -SINFR 0; SINFR CONFR 0;...

8 years ago | 0

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Fitting with coupled differential equations
So I suspect that "pulses" is an (nx2) array with the first column being "time" and the second column being values between 0 and...

8 years ago | 0

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How do I write the function (d^2 θ)/(dt^2 )+sin⁡((θ(t))=0 in Matlab?
syms y(t) Dy = diff(y,t); taylor(dsolve(diff(y,t,2)+sin(y)==0,[y(0)==pi/12,Dy(0)==0]),t,0,'Order',4) Best wishes T...

8 years ago | 0

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How do i plot the function v(t) below :
fplot(@(t)5*exp(2*t).*sin(1000*pi*t),[-1 1]); Best wishes Torsten.

8 years ago | 1

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Why do I get this function warning (Function behaves unexpectedly on array inputs)
function s = camdisp(t) w = 2*(pi/5); for i=1:numel(t) if t(i)>=0 && t(i)<80 s(i) = ((10.*1.25)*((t(i)...

8 years ago | 0

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Answered
Why this happen in using limit, i cant use syms ? someone help me, i need to do my homework, oh god please.
Please execute the "ver" command. You should have something like Symbolic Math Toolbox Vers...

8 years ago | 1

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Answered
how can I find the radius of part of spherical surface
Use fminsearch to determine radius and center of the sphere which approximates your point cloud best (4 unknowns). To this en...

8 years ago | 1

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How to set last solution as initial guess for bvpinit
Setting solinit = sol where "sol" is the solution from which you want to start for the new calculation should work. ...

8 years ago | 0

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Solve differential equations with bvp4c
global F R T e0 Z_Na Z_Cl Z_OH Z_H C_Na_A C_Cl_A C_OH_A C_H_A Cond_A i U_A E_A FixedCharge LA D_H D_OH e_r e % Constant...

8 years ago | 0

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Answered
when running lsqcurvefit to fit the complex function: F = a1*exp(-1i*x*a2) + a3*exp(-1i*x*a4), i get a2 and a4 as complex estimates, however these values should be real. how to solve this?
Write your function F as y = (a11+1i*a12)*(cos(a2*xdata)-1i*sin(a2*xdata))+(a31+1i*a32)*(cos(a4*xdata)-1i*sin(a4*xdata)) = ...

8 years ago | 0

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Doubt in coding a systems of ODEs with bvp4
x''''=A*x+B*y+C*(D*y+E*x+F*x'''') -> x''''=((A+C*E)*x+(B+C*D)*y)/(1-C*F) y''''=D*y+E*x+F*(A*x+B*y+C*y'''') -> y''''=((E+A*F...

8 years ago | 0

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Answered
Curve Fitting Using Outside Parameter
Use ...'problem','n'... in the FitType structure and set "n" to a value in the call to "fit". Best wishes Torsten.

8 years ago | 0

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Error using odearguments (line 113),Error in ode45 (line 115)
ode45 is a numerical solver. So all variables supplied to ode45 in "Cauchy" and "func2" must be of type "single" or "double", no...

8 years ago | 0

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Can I solve Brinkman equation in Matlab?
Use MATLAB's bvp4c. Best wishes Torsten.

8 years ago | 0

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hi,i want to write matlab code for the given eq. plese help me
Here is the definition of the complex normal distribution: https://en.wikipedia.org/wiki/Complex_normal_distribution You u...

8 years ago | 0

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Answered
Good morning please help me :( badly needed
Symbolically, this is not possible since you have 6 equations in 3 unknowns. Try the numeric way to get the least-squares sol...

8 years ago | 0

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The function F2 is not working correctly. I have to solve a second order differential equation and the ODE45 solver in the main function doesnt run. The main function actually takes values from two other functions, so whx is my ODE45 not working ?
In scarg1, allocate F2 as F2 = zeros(2,1) Best wishes Torsten.

8 years ago | 0

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Answered
Index exceeds matrix dimensions?? Error in my script..help please?
You don't initialize fi1(1)=0 Best wishes Torsten.

8 years ago | 0

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How can I integrate a function that has more than 1 input?
fun = @(x)dsACst(x,zeta,nu) q = integral(fun,0,Inf) Best wishes Torsten.

8 years ago | 1

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How can I solve an ode for its particular solution only?
If you know that n = (2/sqrt(6))*F*cos(o*x)/(3/2-o^2) is a (particular) solution of the ODE, just evaluate n and n' at x=0, and ...

8 years ago | 0

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Solving Partial Differential Equation for heat convection equation.
If Tinf is the temperature of the environment and h is the heat transfer coefficient [W/(m^2*K)], pr = h*(ur(1)-Tinf); q...

8 years ago | 0

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I want to know how to create a random sequence respect to the probability density function?
https://en.wikipedia.org/wiki/Inverse_transform_sampling Best wishes Torsten.

8 years ago | 1

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MATRIX divison question to find the mass_inertia matrix
You have 1 equation ((0.5)*(qdot.')*mass_inertia_matrix*qdot=KE) in the four unknowns of the coefficients of the mass inertia m...

8 years ago | 0

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How do i stop pdepe if certain condition is met?
Use the "Events" property in the options structure. Search for the string "Event" under https://de.mathworks.com/help/matl...

8 years ago | 0

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Answered
results is NaN help
You divide by t^0.5. So don't start with t=0, but with t=a small value. Best wishes Torsten.

8 years ago | 0

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Loop for bvp4c function with an unknown parameter
function [] = main() kk=0.5 ; for i=1:60 k=kk; valuePresentstudy = Surfactant(k); kk=kk+...

8 years ago | 1

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Loop for bvp4c function with an unknown parameter
Maybe sol = bvp4c(@(x,y,S)fourode(x,y,S,k),@(ya,yb,S)fourbc(ya,yb,S,k),solinit,options); Otherwise pass k to fourode and f...

8 years ago | 1

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Answered
Possible to use values of ones variables to set boundaries in fmincon?
Since x5(t-1) is also a solution variable, you don't have to include it in beq, but you have to set the coefficient of Aeq corre...

8 years ago | 0

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Answered
Optimize two dependent equations
Use lsqnonlin with the f-vector defined as f=[y1(t1)-y1_obs(t1),y1(t2)-y1_obs(t2),...,y1(tn)-y1_obs(tn),y2(t1)-y2_obs(t1),y...

8 years ago | 0

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How to write a non-standard (four parameter) beta pdf as a symbolic expression?
pd = (x-a)^(q-1)*(b-x)^(r-1)/(beta(q,r)*(b-a)^(q+r-1)) Best wishes Torsten.

8 years ago | 0