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coupled differntial equation using ode45
G = 1; Na = 1; xstart = -1; xend = 1; nx = 51; x = linspace(xstart,xend,nx); solinit = bvpinit(x, [0;0;1;0]); sol = bvp...

2 months ago | 1

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Answered
coupled differntial equation using ode45
syms y mu0 G Na U(y) T0(y) eqn1 = diff(mu0*diff(U,y)) == G; eqn2 = diff(T0,y,2) + Na*mu0*(diff(U,y))^2 == 0; conds1 = [U(-1)=...

2 months ago | 0

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Using tabular data for Curve fitting of function z = f (x, y) with incomplete values of z. These blank z (i, j) automatically takes zero values and this is a problem
green = [5 5 5 5 5 4 4 4 4 1 1 1]; blue = [5 10 15 20 25 5 10 15 20 5 10 15]; yellow = [455 322 261 205 169 410 306 246 191 25...

2 months ago | 1

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Answered
Numerical method of the "fimplicit" function
Since you can specify a mesh density in x- and y- direction, my guess is that the function is simply evaluated on X x Y. Sign ch...

2 months ago | 0

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My roots don't match example roots when solving routh criterion
syms K s p = s^3+9*s^2+12*s+15+3*K; solve(p,s,'MaxDegree',3) var2 = vpa(ans); var = subs(var2,K,-1)

2 months ago | 0

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Answered
Interrupt a while loop with functions if it takes too long
Is there a way of timing the iteration during its execution and break it? No. You could go into the function and time certain o...

2 months ago | 1

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Answered
How to solve the system of time dependent coupled PDE's?
ode23t seems to work for high Reynolds numbers. In case ode23t fails (e.g. for the low Reynolds number regime), I recommend the ...

2 months ago | 1

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Problem with my gamma_water values not giving me the correct pressure using fsolve
Look at the curves and see what's happening. Your first equation has two solutions while your second has none: DelH = -1* (-917...

2 months ago | 0

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An absolutely ascending sequence
x = 0:10; all(diff(x)>0)

2 months ago | 0

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Find zero of simple monotonic function where the independent variable can only be integer
If you know a lower integer value xl and an upper integer value xu with y(xl)*y(xu) < 0, you could do a binary search starting f...

2 months ago | 0

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Model simulation Code for SEIR
seir_simulation() function seir_simulation() % Parameters beta = 0.3; % Effective contact rate without control sigma = 1/5; ...

2 months ago | 0

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using loops and arrays to solve for variables in equations
You mean this ? x=zeros(5,1); vis=zeros(5,1); %strain rate epsUse=1e-14; Puse=1e9; PARAMS.R=8.314; %ideal gas constant %d...

2 months ago | 0

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How to use Matlab to find a pressure in a temperature and density spreadsheet using the nearest density value.
%Generate artificial data t = linspace(10,30, 25); p = linspace(1, 20, 20); [T,P] = ndgrid(t,p); d = exp(-((T-20).^2+(P-10)....

2 months ago | 0

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Kolmogorov-Smirnov (KS) Test
From the documentation: h = kstest(x,Name,Value) returns a test decision for the one-sample Kolmogorov-Smirnov test with additi...

2 months ago | 0

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Solving the hub location problem
You set % Renewal of population population = offspring; and offspring has only size 1x100 instead of 1x186. Thu...

2 months ago | 1

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Why does the value of tolerance stop at n=2 (third value of the iteration) within the while loop?
Maybe you mean tol = 1e-7 instead of tol = exp(-7) ? However: It's correct that MATLAB quits the while-loop after three val...

2 months ago | 1

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Minimization linprog constraint no feasible solution
The last equality constraint says that you want 0*x1 + 0*x2 + 0*x3 + 0*x4 + 0*x5 + 0*x6 + 0*x7 + 0*x8 = 6.6, thus 0 = 6.6 ... ...

2 months ago | 0

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Answered
4th order Runge Kutta Method Differential System
Note that COne and CTwo are given in muF - thus they should be prescribed as 1000e-6 in your code, I guess. COne = 1000e-6; C...

2 months ago | 0

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Error using odearguments Vector Length issue
s3 = s(3) s5 = s(5) instead of s3=(s) s5=s(4)

2 months ago | 0

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Answered
Newton Forward difference method
Three coding errors: % Confirmed case Sample data points (x, y) data = [ 1, 88; 2, 49; 3, 47; 4, 8; 5, 34; 6, 762; 7, 98; 8, ...

2 months ago | 0

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Answered
integral using "int" function
Your code to produce g1, g2 and g3 does not matter. You don't get analytic expressions for the antiderivatives of g1, g2 and g...

2 months ago | 0

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Ode23 is not outputting solutions at the times I specified between t0 and tf in tspan=[t0, t1, t2..., tf]
If you use the "soln" structure as result, ode23 only respects start and end point from your tspan vector. After the integrator...

2 months ago | 0

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Answered
f(x) = x^2/3(3-x^2)(x-4). How do I enter this function in MATLAB?
Replace c = solve(fx); by c = solve(fx*x^(1/3)==0,'Maxdegree',3);

2 months ago | 0

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Problem with integration: there is a pole on a contour
In the usual sense, your integral does not exist. But you can compute its principal value: syms z syms t real f = (z^2+3*z+2...

2 months ago | 2

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Integral2 seems to substitute non-scalar values of variable into integrand. Why?
"integral2" usually calls the function to be integrated with matrices of the same size for t1 and t2 to make the necessary funct...

2 months ago | 2

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Answered
error when using lsqnonlin to function containing fzero function
"K" is a vector because "fraction" is a vector. Thus the "y" you compute in "denaturationfun" is a vector. But "fzero" cannot so...

2 months ago | 0

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Answered
I'm trying to solve jeffry hamel equation using RK4 but it's not giving output as expected.
s = 6; Kn = 0.1; U20 = -1; U2 = fsolve(@(U2)fun_shoot(U2,s,Kn),U20) [Y,Z] = fun_odes(U2,s); plot(Z(:,1),Y) xlabel('U') yl...

2 months ago | 1

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Generalised solution to a n-order system of equations
Here is my code, that provies a range of answers from a to b, inclusive. Besides that you shouldn't give the same names to the ...

2 months ago | 0

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Unconstrained minimisation problem with a complicated range
I'll formulate the problem for one property - a generalization to three properties is obvious. I'll assume that each of the 3*N...

2 months ago | 0

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I'm trying to solve a 2nd order ode with ode45, but have no idea where to start.
After dividing your equation by t, you can just follow the example Solve Nonstiff Equation under https://uk.mathworks.com/hel...

2 months ago | 0