Answered

1D Heat Equation Explicit Scheme (fixed)

With for i=0:0.1:50 you are trying to index variables with zero. However, Matlab's indexing starts at 1.

1D Heat Equation Explicit Scheme (fixed)

With for i=0:0.1:50 you are trying to index variables with zero. However, Matlab's indexing starts at 1.

4 mois ago | 1

Answered

How to plot Homogeneous solution and Particular integral seperately of a second order differntial equation using ode45

ode45 just solves first order equations, so turn your second order equation into two first order ones, like so: y' = v v' = -4...

How to plot Homogeneous solution and Particular integral seperately of a second order differntial equation using ode45

ode45 just solves first order equations, so turn your second order equation into two first order ones, like so: y' = v v' = -4...

4 mois ago | 0

Answered

Trying to plot R_K 4th order, but keep getting straight line?

Check these equations F_sir = @(s,i,r) -a*s*i; % change the function as you desire G_sir = @(...

Trying to plot R_K 4th order, but keep getting straight line?

Check these equations F_sir = @(s,i,r) -a*s*i; % change the function as you desire G_sir = @(...

4 mois ago | 1

| accepted

Answered

Not enough input arguments; fzero function

Replace T_mix = fzero(fun,T_mix_0); by T_mix = fzero(@fun,T_mix_0);

Not enough input arguments; fzero function

Replace T_mix = fzero(fun,T_mix_0); by T_mix = fzero(@fun,T_mix_0);

4 mois ago | 1

Answered

I am trying to use the trapezoidal rule to compute the flow rate of fluid through a pipe.

I think it needs to be more like this: % Velocity distribution function of the pipe % Area = pi*r^2 % dA = 2*pi*r dr % Q = V...

I am trying to use the trapezoidal rule to compute the flow rate of fluid through a pipe.

I think it needs to be more like this: % Velocity distribution function of the pipe % Area = pi*r^2 % dA = 2*pi*r dr % Q = V...

4 mois ago | 0

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Answered

How to get area under the fit attained by Curve Fitting tool?

Try help trapz

How to get area under the fit attained by Curve Fitting tool?

Try help trapz

4 mois ago | 0

Answered

Progressively slower performance and task constraints using matrix and loops

With these particular functions it's easy to precalculate the Jacobian function and do everything numerically (and quickly). Fo...

Progressively slower performance and task constraints using matrix and loops

With these particular functions it's easy to precalculate the Jacobian function and do everything numerically (and quickly). Fo...

4 mois ago | 0

Answered

Local Stiffness Matrix Negative

How about replacing if i==2 & j==2 k=A(e)*E/(L/5); elseif i==2 & j==1 k=...

Local Stiffness Matrix Negative

How about replacing if i==2 & j==2 k=A(e)*E/(L/5); elseif i==2 & j==1 k=...

4 mois ago | 0

Answered

Save array values in a for loop

Try replacing error = max(abs(double(y1-z1(vx)))) with error(i) = max(abs(double(y1-z1(vx))));

Save array values in a for loop

Try replacing error = max(abs(double(y1-z1(vx)))) with error(i) = max(abs(double(y1-z1(vx))));

4 mois ago | 0

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Answered

Solving a PDE with two variables using cank nicolson method

Matlab indices start at 1, so the loops i, j and K in the following for i=0:N for j=0:M for K=0:1 f(x,y...

Solving a PDE with two variables using cank nicolson method

Matlab indices start at 1, so the loops i, j and K in the following for i=0:N for j=0:M for K=0:1 f(x,y...

4 mois ago | 0

Answered

Solving a System of 2nd Order Nonlinear ODEs

You haven't passed y and z to the funcion in function dydt=mbd(M,m,g,lc,k) Probably needs to be more like function dydt=mbd(t...

Solving a System of 2nd Order Nonlinear ODEs

You haven't passed y and z to the funcion in function dydt=mbd(M,m,g,lc,k) Probably needs to be more like function dydt=mbd(t...

4 mois ago | 0

Answered

Can I comment only a section or part of a line?

Like this: x = linspace(0,2*pi,100); y1 = sin(x); y2 = cos(x); plot(x,y1,... % comment x,y2)

Can I comment only a section or part of a line?

Like this: x = linspace(0,2*pi,100); y1 = sin(x); y2 = cos(x); plot(x,y1,... % comment x,y2)

5 mois ago | 0

Answered

Adding subtitle to the plot

In Matlab 2018 try title({'Main title text';'subtitle text'}) (Note the curly brackets)

Adding subtitle to the plot

In Matlab 2018 try title({'Main title text';'subtitle text'}) (Note the curly brackets)

5 mois ago | 0

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Answered

Left-rotating a vector

You define B as a null vector so it doesn't have an "end". Try, simply A = [1,2,3,4,5]; B = [A(2:end) A(1)]

Left-rotating a vector

You define B as a null vector so it doesn't have an "end". Try, simply A = [1,2,3,4,5]; B = [A(2:end) A(1)]

5 mois ago | 0

| accepted

Answered

How can I solve this error : Invalid text character. Check for unsupported symbol, invisible character, or pasting of non-ASCII characters.

This works for me: n=input('donner le nombre de points: '); k=0; for i=1:n u1=rand;u2=rand; x=2*u1; y=2*u2...

How can I solve this error : Invalid text character. Check for unsupported symbol, invisible character, or pasting of non-ASCII characters.

This works for me: n=input('donner le nombre de points: '); k=0; for i=1:n u1=rand;u2=rand; x=2*u1; y=2*u2...

5 mois ago | 0

Answered

Lax-Wendroff method for advection equation with periodic boundary condition

If you make dt=0.1*h/a; instead of dt=0.95*h/a; your max error reduces to 0.0355.

Lax-Wendroff method for advection equation with periodic boundary condition

If you make dt=0.1*h/a; instead of dt=0.95*h/a; your max error reduces to 0.0355.

5 mois ago | 0

Answered

I want to solve the unknown variable t1

Well, this gets it working, though who knows if it makes any sense!" A0 =500; D0=100; c1=5; c2=10; c3=10; c4=8; a=30; a2...

I want to solve the unknown variable t1

Well, this gets it working, though who knows if it makes any sense!" A0 =500; D0=100; c1=5; c2=10; c3=10; c4=8; a=30; a2...

5 mois ago | 0

Answered

How to make convergence plot (error VS time step) in a log-log scale among four numerical methods and exact solution?

This should give you the right idea: %% 1st-order Adams-Bashforh Solution fun = @(t,y) (y); %Function f(t,y) y0 = 1; %Initial...

How to make convergence plot (error VS time step) in a log-log scale among four numerical methods and exact solution?

This should give you the right idea: %% 1st-order Adams-Bashforh Solution fun = @(t,y) (y); %Function f(t,y) y0 = 1; %Initial...

5 mois ago | 0

Answered

i need some help with finding the damping ratio

Use fzero: x = [12.73, 25.36, 37.99]; y = [0.77, 0.29, 0.11]/2; zeta = fzero(@(zeta) fn(zeta,y),0.5); disp(['zeta = ' nu...

i need some help with finding the damping ratio

Use fzero: x = [12.73, 25.36, 37.99]; y = [0.77, 0.29, 0.11]/2; zeta = fzero(@(zeta) fn(zeta,y),0.5); disp(['zeta = ' nu...

5 mois ago | 0

Answered

How to make graph that plot between Analytical Solution (Exact Solution) and Numerical Method Solution?

After Y = exactY(t2) you probably need something like: plot(t2,Y2,t2,Y) legend('AM','Exact') However, you haven't supplied th...

How to make graph that plot between Analytical Solution (Exact Solution) and Numerical Method Solution?

After Y = exactY(t2) you probably need something like: plot(t2,Y2,t2,Y) legend('AM','Exact') However, you haven't supplied th...

5 mois ago | 0

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Answered

How to numerically solve and plot definite integral with variable upper limit

Like so: K= @(t) (sin(t)-t.*cos(t)).*sin(t); P = 0:0.1:3.1416; for i = 1:numel(P) V(i) = integral(K,0,P(i)); ...

How to numerically solve and plot definite integral with variable upper limit

Like so: K= @(t) (sin(t)-t.*cos(t)).*sin(t); P = 0:0.1:3.1416; for i = 1:numel(P) V(i) = integral(K,0,P(i)); ...

6 mois ago | 0

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Answered

merge two matrices after odd rows

Here's one way: A=[1 1;1 1;1 1]; B=[2 3;4 5;6 7]; AB = [A B]'; C = reshape(AB,2,6)'

merge two matrices after odd rows

Here's one way: A=[1 1;1 1;1 1]; B=[2 3;4 5;6 7]; AB = [A B]'; C = reshape(AB,2,6)'

6 mois ago | 0

Answered

Hello, I am trying to solve the ODE but I have an error I do not understand how to solve. Would appreciate some help. Thank you!

Like this? %% ODE45_estimation % ------ Constants ------ % m = 1248.5; g = 9.81; W = m*g; S = 17.1; % ------ Time int...

Hello, I am trying to solve the ODE but I have an error I do not understand how to solve. Would appreciate some help. Thank you!

Like this? %% ODE45_estimation % ------ Constants ------ % m = 1248.5; g = 9.81; W = m*g; S = 17.1; % ------ Time int...

6 mois ago | 0

Answered

plotting Solid of revolution of a function

How about: X = 0:0.1:pi; R = sin(X); [z,x,y] = cylinder(R); surf(x,y,z)

plotting Solid of revolution of a function

How about: X = 0:0.1:pi; R = sin(X); [z,x,y] = cylinder(R); surf(x,y,z)

6 mois ago | 1

Answered

Split an array using specific points

Like this? Y = [5;2;3;6;7;9;5;5;6;3;8;7;74;9;63;47;10;3]; diiv = [5; 9; 15]; y1 = Y(1:diiv(1)); y2 = Y(diiv(1)+1:diiv(2)); ...

Split an array using specific points

Like this? Y = [5;2;3;6;7;9;5;5;6;3;8;7;74;9;63;47;10;3]; diiv = [5; 9; 15]; y1 = Y(1:diiv(1)); y2 = Y(diiv(1)+1:diiv(2)); ...

6 mois ago | 1

Answered

Algorithm for Fractional power calculation

How about using the Newton-Raphson algorithm. Here's the basic idea: % x^n = b % Let f(x) = x^n - b % dfdx(x) = n*x^(n-1) %...

Algorithm for Fractional power calculation

How about using the Newton-Raphson algorithm. Here's the basic idea: % x^n = b % Let f(x) = x^n - b % dfdx(x) = n*x^(n-1) %...

6 mois ago | 0

Answered

Stochastic differential equation Gompertz plotting a graph

You have x(1) = 0, so log(x(1)) is -Inf, which means that subsequent values of x will be NaNs.

Stochastic differential equation Gompertz plotting a graph

You have x(1) = 0, so log(x(1)) is -Inf, which means that subsequent values of x will be NaNs.

6 mois ago | 0

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Answered

Defining integration function in matlanb

Like this? % If Cp is a constant then the integral is just Cp*T % If it is a function of T, then define the function: Cp = @(...

Defining integration function in matlanb

Like this? % If Cp is a constant then the integral is just Cp*T % If it is a function of T, then define the function: Cp = @(...

6 mois ago | 0

Answered

Plotting and coding problems

More like this perhaps: T = 300:0.5:500; w = 0.224; Tc = 304.2; ...

Plotting and coding problems

More like this perhaps: T = 300:0.5:500; w = 0.224; Tc = 304.2; ...

6 mois ago | 0

Answered

I am getting error, "array indices must be positive or logical integer values". Please help

You need multiplication signs between n and (w1+k) in calculations of u and z: [X,Y] = meshgrid(-4:0.2:4); n=2; k=1; %n=1,...

I am getting error, "array indices must be positive or logical integer values". Please help

You need multiplication signs between n and (w1+k) in calculations of u and z: [X,Y] = meshgrid(-4:0.2:4); n=2; k=1; %n=1,...

6 mois ago | 0