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System of differential equations and fitting with lsqcurvefit
function main % loading Exp data CurrentDensity = xlsread('Modified_Current_density_all','Sheet1','A1:J1001'); Brightne...

7 years ago | 0

Answered
HOW TO SOLVE TRANSCENDENTAL EQUATION
function main Enle0 = 1.0; Enle = fzero(@fun,Enle0) end function res = fun(Enle) Vc = 0.249; c = 3e8; m0 = 0....

7 years ago | 1

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Answered
Finding the 'n'-th derivative of a function containing 'n'
syms x k n = 10; diff(exp(-x)*x^(n+k),x,n)

7 years ago | 0

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how to create an vector contains 10000 random values that uniformly distributed with mean 1 and variance 10 ?
mean = 1.0; std = sqrt(10); N = 10000; u = (mean-sqrt(12)/2*std) + sqrt(12)*std*rand(N,1) u is uniformly distributed on [a:...

7 years ago | 0

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Answered
How to run lsqcurvefit with a function handle with 2 array-variables?
rao_H2O = @(k,x) k(1)*k(2)*C_TBA_H2O./(1+k(2)*C_TBA_H2O+(k(2)*C_H2O).^gamma(2))+k(3)*C_TBA_H2O; xdata = zeros(size(rao_norm)); ...

7 years ago | 0

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Can't figure out how to iterate a variable defined in ode45 function.
[time,s] = ode45(@(time,s)dampedspring(time,s,b),tspan,BC);

7 years ago | 0

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A(B)=0 What is its meaning?
All numbers in the matrix A that are bigger than 0.8 are set to 0.

7 years ago | 0

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FALLING FACTORIAL AND POCHHAMMER
prod(x-a+1:x)

7 years ago | 0

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Answered
How to sum all positive values in each row in matrix?
sum(max(A,0),2)

7 years ago | 0

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Answered
Lotto code,the previous number cannot appear again,how do i improve it?
x = rand(1,10); [a b] = sort(x); previous_number = b(1:6) set_for_last_number = setdiff(1:8,previous_number); pos = randi(le...

7 years ago | 0

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Answered
How to find minima from a fitted 3rd order polynomial
Solve y'(x)=0 for x and check whether f''(x) > 0.

7 years ago | 0

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trying to put this integrative function in Matlab, but i dont know how.
alpha = ...; m0 = ...; h1 = ...; h2 = ...; xs = ...: fun = @(x)exp(-h1*abs(alpha)-h2*sqrt(alpha^2+m0^2))*exp(1i*alpha*(x-xs...

7 years ago | 0

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Answered
Fix the maximum number of iterations while using ode solvers
https://de.mathworks.com/matlabcentral/answers/94739-is-it-possible-to-specify-the-maximum-amount-of-time-or-number-of-function-...

7 years ago | 0

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Answered
MATLAB solving BVP using bvp4c, variable coefficient
If you make the ansatz f ( r ) = a0 + a1*r + a2*r^2 + ...+ an *r^n you will need (n+1) additional boundary conditions to fix ...

7 years ago | 0

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Error in using * in Non-linear regression
Elementwise multiplication is required: modelfun = @(b,x) b(1)*(x(:,1).^b(2)).*(x(:,2).^b(3)).*(x(:,3).^b(4));

7 years ago | 0

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Answered
IMPOSING CONSTRAINTS in FMINCON
A=[0 1 1 0; 0 1 -1 0]; b=[1;0];

7 years ago | 0

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BVP PROBLEM how can we take 'c' in x-axis(continuous range.[-1.3:0.02:-1.1]) and to find f"(0)
function main S = 1; c = [-1.3:0.02:-1.1]; Pr = 0.7; n = -0.8; sol = zeros(numel(c),1); x = [3 -1]; ...

7 years ago | 0

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Answered
problem solving nonlinear equation system with fsolve
Try Maugis = @(X) [lambda*X(1)^2/2*(sqrt(X(3)^2-1)+(X(3)^2-2)*atan(sqrt(X(3)^2-1)))+4/3*lambda^2*X(1)*(sqrt(X(3)^2-1)*atan(sqrt...

7 years ago | 0

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Answered
Why does my rand function not seem to work?
You will never hit 0.3266 exactly using the "rand" command. You can use if abs(tmp-limit) < 1e-6 or something similar in you...

7 years ago | 1

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Answered
How to calculate an integral with an infinite series inside?
I get I = sum_{n=1}^{n=Inf} (1-exp(-4*n^2*t))/(4*n^2) I don't know if an analytical solution exists. Best wishes Torsten.

7 years ago | 0

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How can I integrate a function which was generated by a smoothing spline?
int(i,1)=integral(@(x)feval(f,x),1.2,1.6);

7 years ago | 1

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Answered
Runge- kutta Help on solving end order Differential equation
function RungeKuttaMethod a = 0; %time interval we are solving over b = 4; N = 1000; %...

7 years ago | 1

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2nd Order Nonlinear Differential Equation Solving with Central Difference Method?
http://web.mit.edu/10.001/Web/Course_Notes/Differential_Equations_Notes/node9.html

7 years ago | 1

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Nonlinear 2nd order ODE with term x^2*y'' and initial value y(0)=20
https://en.wikipedia.org/wiki/Cauchy%E2%80%93Euler_equation The section Second order – solution through change of variables s...

7 years ago | 0

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Numerically solve of integral equation with known Integrand
If d2z_p(i) = dv_p / dtau at tau = i * t / n = i * dt and d2z_f(i) = dv_f / dtau at tau = i * t / n = i * dt in your code from a...

7 years ago | 1

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Answered
RK4 method for system of ODEs
https://www.google.de/search?source=hp&ei=E994XNKfMYPKwALsyYLwAw&q=matlab+%26+rk4+code&btnK=Google-Suche&oq=matlab+%26+rk4+code&...

7 years ago | 0

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Solve a system of equations
function main x0=zeros(8,1); sol=fminsearch(@(x)fun(x(1),x(2),x(3),x(4),x(5),x(6),x(7),x(8)),x0) sol=fminsearch(@(x)fun(x(1),...

7 years ago | 0

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Answered
In Ode15s, how do I break the time span into smaller intervals and call the solver twice, so that the integration proceeds faster?
tspan1=[t0 t1]; [ta,y1]=ode15s(@odefun,tspan1,initialCond,solverOptions,additionalParams); initialCond=y1(end,:); tspan2=[t1 ...

7 years ago | 1

Answered
Warning: Reached the limit on the maximum number of intervals in use. Approximate bound on error is 2.4e+02. The integral may not exist, or it may be difficult to approximate numerically to the requested accuracy.
E1=@(x)besselj(0,r/d.*x).*sqrt(x.*tanh(x)).*x.*sin(sqrt(9.81*t(i)^2/d.*x.*tanh(x))).*(sin(a/d.*x)-a./d.*x.*cos(a/d.*x))./(a/d.*x...

7 years ago | 1

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less time to run how
Usually, fun is called for a vector of x-values and must return an array of the same size. ArrayValued = true forces "integral" ...

7 years ago | 0