Answered

Optimisation of parameters in a PDE

https://de.mathworks.com/matlabcentral/answers/406938-fitting-the-numerical-solution-of-a-pde-with-one-parameter-to-some-data ...

Optimisation of parameters in a PDE

https://de.mathworks.com/matlabcentral/answers/406938-fitting-the-numerical-solution-of-a-pde-with-one-parameter-to-some-data ...

4 days ago | 0

Answered

How would I solve a Laplace Equation using the FDM method?

Solve A*V=b where A, b result from the system of equations V(1) = V0 (V(i+1)-2*V(i)+V(i-1))/h^2 = 24*x(i) (i=2,...,Nx) ...

How would I solve a Laplace Equation using the FDM method?

Solve A*V=b where A, b result from the system of equations V(1) = V0 (V(i+1)-2*V(i)+V(i-1))/h^2 = 24*x(i) (i=2,...,Nx) ...

4 days ago | 0

Answered

By what I can replace randint() function.

r = rand(1,1); k = min(floor(10*r),9)+5

By what I can replace randint() function.

r = rand(1,1); k = min(floor(10*r),9)+5

4 days ago | 0

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Answered

How to solve this equation?

fun=@(i)400000000*(1+i)^-1+500000000*(1+i)^-2+760000000*(1+i)^-3+200000000*(1+i)^-4+140000000*(1+i)^-5+3105237.5*((1+i)^46-1)/...

How to solve this equation?

fun=@(i)400000000*(1+i)^-1+500000000*(1+i)^-2+760000000*(1+i)^-3+200000000*(1+i)^-4+140000000*(1+i)^-5+3105237.5*((1+i)^46-1)/...

4 days ago | 0

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Answered

I want to program (solve this equation for h) this problem in Matlab but I do not know the appropriate function to use.

h can be explicitly solved for: par.Vp = 26.01; m_Lp = 24973; hss =0.96; par.Alpha_Lp_av = pi/180; par.theta = ...

I want to program (solve this equation for h) this problem in Matlab but I do not know the appropriate function to use.

h can be explicitly solved for: par.Vp = 26.01; m_Lp = 24973; hss =0.96; par.Alpha_Lp_av = pi/180; par.theta = ...

5 days ago | 1

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Answered

Error using pdepe (line 293) Spatial discretization has failed.

Try function Kronstadt_HW4_problem3_pdepe %This is a dimensional formulation close all Nx=201; ...

Error using pdepe (line 293) Spatial discretization has failed.

Try function Kronstadt_HW4_problem3_pdepe %This is a dimensional formulation close all Nx=201; ...

5 days ago | 2

| accepted

Answered

A PDE equation giving meaningless results

Try function main % simple PDE % Equation: dC/dt = K * d^2C/dx^2 - kr * C % IC: C0 = 0.762471166 ...

A PDE equation giving meaningless results

Try function main % simple PDE % Equation: dC/dt = K * d^2C/dx^2 - kr * C % IC: C0 = 0.762471166 ...

5 days ago | 0

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Answered

How are initial values chosen for either lsqcurvefit or nlinfit functions?

There must be some mathematical operation within your objective function that gives Inf, NaN or something similar (e.g. division...

How are initial values chosen for either lsqcurvefit or nlinfit functions?

There must be some mathematical operation within your objective function that gives Inf, NaN or something similar (e.g. division...

5 days ago | 0

Answered

differentiation for a function

syms x y(x) diff(x-y^2,x) Best wishes Torsten.

differentiation for a function

syms x y(x) diff(x-y^2,x) Best wishes Torsten.

6 days ago | 0

Answered

how to stop dde23 when one of states reach certain value?

Use the "Events" option of dde23. Best wishes Torsten.

how to stop dde23 when one of states reach certain value?

Use the "Events" option of dde23. Best wishes Torsten.

6 days ago | 1

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Answered

How to set open boundary conditions with Pdepe for advection-diffusion-reaction of concentrations?

Choose your interval where you solve your equations big enough. This way, you won't come into trouble with the boundary conditio...

How to set open boundary conditions with Pdepe for advection-diffusion-reaction of concentrations?

Choose your interval where you solve your equations big enough. This way, you won't come into trouble with the boundary conditio...

7 days ago | 1

| accepted

Answered

simultaneous fitting of two plots with two functions

xdata=[x(:,1); x(:,1)]; ydata=[y1(:,1); y2(:,1)]; fun=@(x,xdata) [f1(xdata(1:numel(xdata)/2),x(1),x(2),x(3),x(4)); f2(x...

simultaneous fitting of two plots with two functions

xdata=[x(:,1); x(:,1)]; ydata=[y1(:,1); y2(:,1)]; fun=@(x,xdata) [f1(xdata(1:numel(xdata)/2),x(1),x(2),x(3),x(4)); f2(x...

7 days ago | 0

Answered

simultaneous fitting of two plots with two functions

Use "lsqcurvefit" with the data set xdata = (x,x),ydata = (y1,y2). Best wishes Torsten.

simultaneous fitting of two plots with two functions

Use "lsqcurvefit" with the data set xdata = (x,x),ydata = (y1,y2). Best wishes Torsten.

7 days ago | 0

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Answered

Is it possible to use DuDx as boundary condition in pdepe if DuDx doesn't appear in the equation in a system of PDE/ODE?

Mathematically, an ODE does not need a boundary condition - the value of an ODE in a boundary point is given by solving the ODE ...

Is it possible to use DuDx as boundary condition in pdepe if DuDx doesn't appear in the equation in a system of PDE/ODE?

Mathematically, an ODE does not need a boundary condition - the value of an ODE in a boundary point is given by solving the ODE ...

7 days ago | 1

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Answered

1st order differential equation , boundary conditions

syms y1(t) y2(t) eqn = [diff(y1,t) == y2*y1*log(450/y1), diff(y2,t) == 0]; cond = [y1(0)==40, y1(15)==95]; [y1Sol(t) ...

1st order differential equation , boundary conditions

syms y1(t) y2(t) eqn = [diff(y1,t) == y2*y1*log(450/y1), diff(y2,t) == 0]; cond = [y1(0)==40, y1(15)==95]; [y1Sol(t) ...

10 days ago | 0

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Answered

1st order differential equation

This is a boundary value problem - use "bvp4c" instead of "ode45". Or try "dsolve". Best wishes Torsten.

1st order differential equation

This is a boundary value problem - use "bvp4c" instead of "ode45". Or try "dsolve". Best wishes Torsten.

10 days ago | 0

Answered

Problem of integral combined with fzero

Instead of specifying a point (0.01) in the call to "fzero", you should specify a search interval which excludes the point c0=0....

Problem of integral combined with fzero

Instead of specifying a point (0.01) in the call to "fzero", you should specify a search interval which excludes the point c0=0....

10 days ago | 0

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Answered

could anyone help me to solve the issue in the following code

X=[3] for t=1:length(X) A = partitions([X(t)]) for d=1:length(A) if length(A{d})>1 for e=1:leng...

could anyone help me to solve the issue in the following code

X=[3] for t=1:length(X) A = partitions([X(t)]) for d=1:length(A) if length(A{d})>1 for e=1:leng...

11 days ago | 1

| accepted

Answered

How can I solve a system of differential equations of second order?

Write your system as w1' = w2 w2' = k*(w4*B3(w1,w3,w5)-w6*B2(w1,w3,w5)) w3' = w4 w4' = k*(w6*B1(w1,w3,w5)-w2*B3(w1...

How can I solve a system of differential equations of second order?

Write your system as w1' = w2 w2' = k*(w4*B3(w1,w3,w5)-w6*B2(w1,w3,w5)) w3' = w4 w4' = k*(w6*B1(w1,w3,w5)-w2*B3(w1...

11 days ago | 0

Answered

CDF and Inverse CDF of Wrapped Cauchy Distribution

function main p = linspace(0,1,11); prob = linspace(0,1,100); x = zeros(numel(p),numel(prob)); for ...

CDF and Inverse CDF of Wrapped Cauchy Distribution

function main p = linspace(0,1,11); prob = linspace(0,1,100); x = zeros(numel(p),numel(prob)); for ...

13 days ago | 1

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Answered

matlab pdepe boundary conditions help

"pdepe" is a solver for parabolic/elliptic partial differential equations of 2nd order. Your equations are hyperbolic equations ...

matlab pdepe boundary conditions help

"pdepe" is a solver for parabolic/elliptic partial differential equations of 2nd order. Your equations are hyperbolic equations ...

13 days ago | 0

Answered

Multiple parameters optimization having calculated and experimental values

function main P_k = ...; Hcexp = ...; T_k = ...; z = ...; w = ...; v = ...; c = ...; a...

Multiple parameters optimization having calculated and experimental values

function main P_k = ...; Hcexp = ...; T_k = ...; z = ...; w = ...; v = ...; c = ...; a...

17 days ago | 1

| accepted

Answered

How to find the exact solution of heat equation U_t=U_xx bc U(0,t)=0=U(1,t), U(x,0)=sin(pix). Also Matlab code?

Easy: fun = @(x,t)sin(pi*x).*exp(-pi^2*t); x = linspace(0,1,50); t = [0.0 0.1 0.2]; [X,T] = meshgrid(x,t); U = ...

How to find the exact solution of heat equation U_t=U_xx bc U(0,t)=0=U(1,t), U(x,0)=sin(pix). Also Matlab code?

Easy: fun = @(x,t)sin(pi*x).*exp(-pi^2*t); x = linspace(0,1,50); t = [0.0 0.1 0.2]; [X,T] = meshgrid(x,t); U = ...

17 days ago | 0

Answered

Create a vector z with 1000 elements generated by the rand-function. The generated values must have a mean value of 0.5 (mean(0.5)). And a standard deviation of sqrt(1/100*12), (std(x)).

0.5*(a+b) = 0.5 1/12*(b-a)^2 = 0.12 Solve for a and b. This will give you the interval [a b] for which you must gener...

Create a vector z with 1000 elements generated by the rand-function. The generated values must have a mean value of 0.5 (mean(0.5)). And a standard deviation of sqrt(1/100*12), (std(x)).

0.5*(a+b) = 0.5 1/12*(b-a)^2 = 0.12 Solve for a and b. This will give you the interval [a b] for which you must gener...

17 days ago | 2

Answered

Differential Equation with Coefficients as Integral Functions

fun=@(x,y)[y(2);-y(2)*integral(@(z)z.^2+3*z-1,0,x)]; is a suitable function to be used with ODE45, and it represents your d...

Differential Equation with Coefficients as Integral Functions

fun=@(x,y)[y(2);-y(2)*integral(@(z)z.^2+3*z-1,0,x)]; is a suitable function to be used with ODE45, and it represents your d...

17 days ago | 1

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Answered

calculating sum of an array by using if-or statement in matlab

Deger = [20 25 27 28 31 32 33 34]; Node1 = [1 2 5 6 7 4 3 3]; Node2 = [2 5 6 7 4 3 2 6]; minimum = min(min(Node1),min...

calculating sum of an array by using if-or statement in matlab

Deger = [20 25 27 28 31 32 33 34]; Node1 = [1 2 5 6 7 4 3 3]; Node2 = [2 5 6 7 4 3 2 6]; minimum = min(min(Node1),min...

17 days ago | 0

| accepted

Answered

how to define an integral function

fun=@(z)z.^2+3*z-1; F=@(x)integral(fun,0,x); F(10)

how to define an integral function

fun=@(z)z.^2+3*z-1; F=@(x)integral(fun,0,x); F(10)

18 days ago | 1

| accepted

Answered

Square of 20 random number sum up to 1

r = r / sqrt(sum(r.^2)) Best wishes Torsten.

Square of 20 random number sum up to 1

r = r / sqrt(sum(r.^2)) Best wishes Torsten.

18 days ago | 0

Answered

How to fit a curve with negative powers of x

If you want to fit parameters a0,...,an to a function of the form y = a0 + a1*x^(-1) + a2*x^(-2) + ... + an*x^(-n) you c...

How to fit a curve with negative powers of x

If you want to fit parameters a0,...,an to a function of the form y = a0 + a1*x^(-1) + a2*x^(-2) + ... + an*x^(-n) you c...

18 days ago | 0

Answered

could anyone help me how to write the bell number equation in matlab

nfinal = 10; b(1)=1; for i=2:nfinal+1 b(i)=0.0; for j=0:i-2 b(i)=b(i)+nchoosek(i-2,j)*b(j+1) end ...

could anyone help me how to write the bell number equation in matlab

nfinal = 10; b(1)=1; for i=2:nfinal+1 b(i)=0.0; for j=0:i-2 b(i)=b(i)+nchoosek(i-2,j)*b(j+1) end ...

19 days ago | 0

| accepted