Answered

Unable to perform assignment because the left and right sides have a different number of elements

Like this? % 1. Define Initial Conditions N = 50; % x_0 = 50*pi/180*randn(2,N); phi_0 = x_0(1,:...

Unable to perform assignment because the left and right sides have a different number of elements

Like this? % 1. Define Initial Conditions N = 50; % x_0 = 50*pi/180*randn(2,N); phi_0 = x_0(1,:...

19 hours ago | 0

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Answered

euler method for solving system of ODE's 1st order

Simple Euler inaccurate for large step size. Reduce step size as in following and see if you get the output you expect: a=0; %...

euler method for solving system of ODE's 1st order

Simple Euler inaccurate for large step size. Reduce step size as in following and see if you get the output you expect: a=0; %...

3 days ago | 1

Answered

How to stop ODE(R4K) function when the value is close to 0?

Have you tried replacing u_p(i+1)=u_p(i)+h/6*(k1u_p+ 2*k2u_p + 2*k3u_p +k4u_p); with u_p(i+1)= max(u_p(i)+h/6*(k1u_p+ 2*k2u_p...

How to stop ODE(R4K) function when the value is close to 0?

Have you tried replacing u_p(i+1)=u_p(i)+h/6*(k1u_p+ 2*k2u_p + 2*k3u_p +k4u_p); with u_p(i+1)= max(u_p(i)+h/6*(k1u_p+ 2*k2u_p...

4 days ago | 0

Answered

how can i solve this problem and plotting?

I assume you want to find the values of a that make the integral = 75, for all values of x. if so, then the following should do...

how can i solve this problem and plotting?

I assume you want to find the values of a that make the integral = 75, for all values of x. if so, then the following should do...

4 days ago | 1

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Answered

speeding up my for loop

Is this any quicker? function y = divisors1(N) i = 1:floor(N/2); L = lcm(N,i); y = sum(L==N) + 1; e...

speeding up my for loop

Is this any quicker? function y = divisors1(N) i = 1:floor(N/2); L = lcm(N,i); y = sum(L==N) + 1; e...

4 days ago | 0

Answered

Mark the knee point on a graph

Calculate a vector of values of P = V.*I then choose the maximum. Something like: P = V.*I; indx = find(P==max(P)); Vp = V(in...

Mark the knee point on a graph

Calculate a vector of values of P = V.*I then choose the maximum. Something like: P = V.*I; indx = find(P==max(P)); Vp = V(in...

5 days ago | 0

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Answered

Discretising a size distribution function and area under the curve

You should have log(sigma)^2, not log(sigma^2). Don't forget the "dx" part when integrating the curve. mu = 0.015; % geometri...

Discretising a size distribution function and area under the curve

You should have log(sigma)^2, not log(sigma^2). Don't forget the "dx" part when integrating the curve. mu = 0.015; % geometri...

5 days ago | 1

Answered

ODE system initial condition results in infinity/NaN error. Initial conditions cannot be changed. How to evade?

Simply write your differential function as: fu_p = @(D_p,u_p) -18*muG*u_p/(rhoP*D_p^2) + g*(rhoP-rhoG)/rhoP; avoiding any expl...

ODE system initial condition results in infinity/NaN error. Initial conditions cannot be changed. How to evade?

Simply write your differential function as: fu_p = @(D_p,u_p) -18*muG*u_p/(rhoP*D_p^2) + g*(rhoP-rhoG)/rhoP; avoiding any expl...

5 days ago | 0

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Answered

Single bubble expansion equation

Try starting your bubble radius as 2*sigma/1.4, rather than 0.

Single bubble expansion equation

Try starting your bubble radius as 2*sigma/1.4, rather than 0.

6 days ago | 0

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Answered

Coupled rate ODEs with ode45

It can all be done in one script as follows. Because of the orders of magntude difference between the various concentrations th...

Coupled rate ODEs with ode45

It can all be done in one script as follows. Because of the orders of magntude difference between the various concentrations th...

7 days ago | 0

Answered

How can I call the highest order solution (e.g. x'') of an ode in another ode?

You can rearrange the equations as follows to get a consistent set: (you will need to use explicit multiplication where my eq...

How can I call the highest order solution (e.g. x'') of an ode in another ode?

You can rearrange the equations as follows to get a consistent set: (you will need to use explicit multiplication where my eq...

7 days ago | 0

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Answered

How can I make a loop that gives values in each iteration?

Why do you need a loop? There is just one zero between 2 and 8. Your values of w are not used in any meaningful way (they woul...

How can I make a loop that gives values in each iteration?

Why do you need a loop? There is just one zero between 2 and 8. Your values of w are not used in any meaningful way (they woul...

7 days ago | 0

Answered

How to use ODE 45 to generate a SIR model

Like so: alpha=1.99; beta=1; gamma=1/7; S=0.99; I=0.01; R=0.1; %tstart=0; %tend=100; y=[S,I,R]; tspan=0:1:100; [t,sol...

How to use ODE 45 to generate a SIR model

Like so: alpha=1.99; beta=1; gamma=1/7; S=0.99; I=0.01; R=0.1; %tstart=0; %tend=100; y=[S,I,R]; tspan=0:1:100; [t,sol...

8 days ago | 2

Answered

error in using the function fsolve to find steady state

Using the Optimization toolbox to solve these equations seems like using a sledgehammer to crack a nut! It is clear from the eq...

error in using the function fsolve to find steady state

Using the Optimization toolbox to solve these equations seems like using a sledgehammer to crack a nut! It is clear from the eq...

8 days ago | 0

Answered

I am trying to solve ODE having more than 1 dependent variable. but I am not able to solve it with dsolve function. please help me to find correct function to solve ODE.This is an mechanical engineering equation so it is bit complicated and lengthy

Here's a possible way using ode45. I've used arbitrary initial values for the three temperatures, so you will need to replace t...

I am trying to solve ODE having more than 1 dependent variable. but I am not able to solve it with dsolve function. please help me to find correct function to solve ODE.This is an mechanical engineering equation so it is bit complicated and lengthy

Here's a possible way using ode45. I've used arbitrary initial values for the three temperatures, so you will need to replace t...

8 days ago | 1

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Answered

MATLAB Newton Raphson Method with a function with array/matrix variables

You could do it like this f = @(x,g) g.*exp(x) - 1; df = @(x,g) g.*exp(x); g = [1 2 3 4 5]; for i= 1:numel(g) x0 = 0...

MATLAB Newton Raphson Method with a function with array/matrix variables

You could do it like this f = @(x,g) g.*exp(x) - 1; df = @(x,g) g.*exp(x); g = [1 2 3 4 5]; for i= 1:numel(g) x0 = 0...

8 days ago | 1

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Answered

When i try to create function error "Unable to perform assignment because the left and right sides have a different number of elements." comes up

Try n=-25:25; x3=zeros(1,length(n)); x3(n>=2 & n<=22)=exp(j*(0.5)).^(2:22);

When i try to create function error "Unable to perform assignment because the left and right sides have a different number of elements." comes up

Try n=-25:25; x3=zeros(1,length(n)); x3(n>=2 & n<=22)=exp(j*(0.5)).^(2:22);

8 days ago | 0

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Answered

Explicit Eulers Method for time advancement

T(i)^(n+1) This will raise T(i) to the (n+1)th power! You need another loop for time (say j = 1:something), then you can refer...

Explicit Eulers Method for time advancement

T(i)^(n+1) This will raise T(i) to the (n+1)th power! You need another loop for time (say j = 1:something), then you can refer...

8 days ago | 0

Answered

Hot to fit two curves under interdependent constraint ?

How about just using fminsearch x = linspace(1,100,100); % Measurement results: y1=[0.07469056,0.07378624,0.07288704,0.071992...

Hot to fit two curves under interdependent constraint ?

How about just using fminsearch x = linspace(1,100,100); % Measurement results: y1=[0.07469056,0.07378624,0.07288704,0.071992...

9 days ago | 0

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Answered

Need assistance using bisection method to find equation roots in Matlab function.

Try this % input for function that we're finding the roots of f1 = @(x) ((-0.6)*x^2)+(2.4*x)+(5.5); xl = 5; % xl sets the i...

Need assistance using bisection method to find equation roots in Matlab function.

Try this % input for function that we're finding the roots of f1 = @(x) ((-0.6)*x^2)+(2.4*x)+(5.5); xl = 5; % xl sets the i...

9 days ago | 0

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Answered

Errors in Newton Raphson Code

Again, more like this % f = 3*exp(x)-4*cos(x) % df/dx = 3*exp(x)+4*sin(x) i=1; x=0.1; err = 1; while err>10^-8 && i<100 ...

Errors in Newton Raphson Code

Again, more like this % f = 3*exp(x)-4*cos(x) % df/dx = 3*exp(x)+4*sin(x) i=1; x=0.1; err = 1; while err>10^-8 && i<100 ...

9 days ago | 0

Answered

Error in Newton-Raphson Method

Like this R=15/2; v=500; h=8; i=1; err = 1; while err>10^-8 && i<100 hold = h; fh = pi*h^2*(3*R - h)/3 - v; ...

Error in Newton-Raphson Method

Like this R=15/2; v=500; h=8; i=1; err = 1; while err>10^-8 && i<100 hold = h; fh = pi*h^2*(3*R - h)/3 - v; ...

9 days ago | 0

Answered

Plotting partial sums of series

Do you mean something like this? x = -pi:0.1:pi ; %initializing x S = zeros(20,numel(x)); figure xlim([1 20]) grid hold o...

Plotting partial sums of series

Do you mean something like this? x = -pi:0.1:pi ; %initializing x S = zeros(20,numel(x)); figure xlim([1 20]) grid hold o...

9 days ago | 0

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Answered

Anonymous function surface plot

Are you looking for something like this? n = 2; x_opt = randi([-6,6],n,1); A = randi(n,n); T = A*A' + eye(n,n); h = -T*x_op...

Anonymous function surface plot

Are you looking for something like this? n = 2; x_opt = randi([-6,6],n,1); A = randi(n,n); T = A*A' + eye(n,n); h = -T*x_op...

10 days ago | 1

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Answered

Solving system of ODEs and Plotting

Something like this? timerange= [0 60]; [t, hvl] = ode45(@f, timerange, [0.9,0.1,0.2]); plot(t, hvl, 'LineWidth', 2),grid ...

Solving system of ODEs and Plotting

Something like this? timerange= [0 60]; [t, hvl] = ode45(@f, timerange, [0.9,0.1,0.2]); plot(t, hvl, 'LineWidth', 2),grid ...

11 days ago | 0

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Answered

Plot 3D of a function

Are you looking for something like this? x = linspace(0,pi); t = linspace(0,1); z = @(x,t) 10*exp(-4*t).*sin(2*x); [x1, t1] ...

Plot 3D of a function

Are you looking for something like this? x = linspace(0,pi); t = linspace(0,1); z = @(x,t) 10*exp(-4*t).*sin(2*x); [x1, t1] ...

12 days ago | 0

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Answered

Error using _*_. What am I doing wrong?

You need dots before the * and before the / , not after the t.

Error using _*_. What am I doing wrong?

You need dots before the * and before the / , not after the t.

12 days ago | 1

Answered

Runge Kutta 4th Order Example

First, write your equation as two first order equations; xdot = v, say, and vdot = -9xdot - 0.1x^3 Then define two functions ...

Runge Kutta 4th Order Example

First, write your equation as two first order equations; xdot = v, say, and vdot = -9xdot - 0.1x^3 Then define two functions ...

12 days ago | 1

Answered

Find intersection point between a vertical line and another line.

You could insert a conditional: AlineX=[0 0]; AlineY=[0 400]; BLineX=[1180 570]; BLineY=[-289.5 250]; p1 = polyfit(Alin...

Find intersection point between a vertical line and another line.

You could insert a conditional: AlineX=[0 0]; AlineY=[0 400]; BLineX=[1180 570]; BLineY=[-289.5 250]; p1 = polyfit(Alin...

12 days ago | 1

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