Answered

How to simplify a symbolic equation, but still keep the denominator

Hi LZ syms x y a b eqn1 = b*(x/a + 1) == b*y/a; % This is the equation, I would like to cancel "b" at both side, and still kee...

How to simplify a symbolic equation, but still keep the denominator

Hi LZ syms x y a b eqn1 = b*(x/a + 1) == b*y/a; % This is the equation, I would like to cancel "b" at both side, and still kee...

1 day ago | 1

Answered

Eliminating and counting rows that contain a pattern that already appeared

Hello Spencer, I assume that the patterns you mean have a length of 5. The way that you have set the the problem, 44313 (B row...

Eliminating and counting rows that contain a pattern that already appeared

Hello Spencer, I assume that the patterns you mean have a length of 5. The way that you have set the the problem, 44313 (B row...

1 day ago | 0

Answered

Fast Fourier Transform component detection issue

Hello awezmm, This occurs because of a combination of aliasing and the spacing of the chosen frequencies. For sampling frequen...

Fast Fourier Transform component detection issue

Hello awezmm, This occurs because of a combination of aliasing and the spacing of the chosen frequencies. For sampling frequen...

6 days ago | 1

| accepted

Answered

My code won't run, related to ode function

Hi Dardenella, try the same thing only with [t,Y] = ode45(@(t,Y) f(t,Y,omega0,p), [0,10],[y0,v0]); % solve for 0<t<10 [n...

My code won't run, related to ode function

Hi Dardenella, try the same thing only with [t,Y] = ode45(@(t,Y) f(t,Y,omega0,p), [0,10],[y0,v0]); % solve for 0<t<10 [n...

8 days ago | 0

Answered

How to make specific elements in a 3D matrix zero?

Hi Rabia, try for yy=1:10 temp = Costyearlydata(:,:,yy); temp(D(:,1,yy)) = 0; cost1(:,:,yy) = temp; end

How to make specific elements in a 3D matrix zero?

Hi Rabia, try for yy=1:10 temp = Costyearlydata(:,:,yy); temp(D(:,1,yy)) = 0; cost1(:,:,yy) = temp; end

8 days ago | 0

| accepted

Answered

constructing a difficult large matrix

Hi ektor, I presume you are interested not so much in the in the matrix A as in the 1000 scalars you get after you multiply eac...

constructing a difficult large matrix

Hi ektor, I presume you are interested not so much in the in the matrix A as in the 1000 scalars you get after you multiply eac...

9 days ago | 0

| accepted

Answered

Plot the travel for an electron by using ode45 (involving matrices)

Hi Ibrahim, There is nothing wrong with using matrices in this situation, and the plot is fine, insofar as it is plotting what ...

Plot the travel for an electron by using ode45 (involving matrices)

Hi Ibrahim, There is nothing wrong with using matrices in this situation, and the plot is fine, insofar as it is plotting what ...

9 days ago | 1

| accepted

Answered

Solver Equation not giving solution

Hi Diogo, Matlab syms can solve this, but it needs some help, which is squaring both sides of eqn3 to form a new eqn3. Also si...

Solver Equation not giving solution

Hi Diogo, Matlab syms can solve this, but it needs some help, which is squaring both sides of eqn3 to form a new eqn3. Also si...

9 days ago | 0

Answered

Mutual Inductance ODEs and wireless power transfer

Hello Tucker, You have two first order DE's so there is no need to have a vector x with four components. Four is appropriate f...

Mutual Inductance ODEs and wireless power transfer

Hello Tucker, You have two first order DE's so there is no need to have a vector x with four components. Four is appropriate f...

10 days ago | 0

Answered

Can anyone help me to fix my code?

Hello JCam, Since you are looking for a numerical result there is really no reason to use syms here. With x and y both being 1...

Can anyone help me to fix my code?

Hello JCam, Since you are looking for a numerical result there is really no reason to use syms here. With x and y both being 1...

10 days ago | 0

Answered

Strange disagreement between analytical phase and unwrap(angle())

Hello Joshua, There a a couple of issues with the analytic calculation. Xkabs = abs( Ampl*sin((pi*L/N)*(k-1)*dn)./sin((pi/N...

Strange disagreement between analytical phase and unwrap(angle())

Hello Joshua, There a a couple of issues with the analytic calculation. Xkabs = abs( Ampl*sin((pi*L/N)*(k-1)*dn)./sin((pi/N...

11 days ago | 0

| accepted

Answered

Plotting complex roots of polynomial

Hi Thomas, what the roots function is looking for is the coefficients of the powers of z in decreasing order. In this case tha...

Plotting complex roots of polynomial

Hi Thomas, what the roots function is looking for is the coefficients of the powers of z in decreasing order. In this case tha...

12 days ago | 0

Answered

Problem with cholesky decomposition

Hi Peter, when you use the 'lower' option, chol assumes that the upper triangle is the complex conjugate transpose of the lower...

Problem with cholesky decomposition

Hi Peter, when you use the 'lower' option, chol assumes that the upper triangle is the complex conjugate transpose of the lower...

12 days ago | 1

| accepted

Answered

Refractive index profile calculation

Hi Tay, The following code addresses (1) in the text. For Lf = 1, D = 1 and 1000 layers the resulting plot reproduces the one ...

Refractive index profile calculation

Hi Tay, The following code addresses (1) in the text. For Lf = 1, D = 1 and 1000 layers the resulting plot reproduces the one ...

12 days ago | 1

| accepted

Answered

Swapping the columns of a matrix with every other column

Hi Robert, Going with permutaions of the first six columns in conjuction with permutations of the last four columns certainly r...

Swapping the columns of a matrix with every other column

Hi Robert, Going with permutaions of the first six columns in conjuction with permutations of the last four columns certainly r...

13 days ago | 1

| accepted

Answered

How to find all the non unique solutions in rank deficient system of linear equations in matlab

Hello Zeab, One solution is v0 = A\b. Since A is rank defiicient it has a nonempty null space nullA = null(A) which is dime...

How to find all the non unique solutions in rank deficient system of linear equations in matlab

Hello Zeab, One solution is v0 = A\b. Since A is rank defiicient it has a nonempty null space nullA = null(A) which is dime...

16 days ago | 1

Answered

How to solve coupled ODE problem

Hi seoyeon, It's easy enough to solve for Ydot4 in the fourth equation. Then if you put that up front in the code, you can plu...

How to solve coupled ODE problem

Hi seoyeon, It's easy enough to solve for Ydot4 in the fourth equation. Then if you put that up front in the code, you can plu...

20 days ago | 0

Answered

How to extract the coefficient of x inside the exponential?

Hi Ishan, Squaring y gives 16 terms involving the product of two exponential functions. Multilying exponentials means adding t...

How to extract the coefficient of x inside the exponential?

Hi Ishan, Squaring y gives 16 terms involving the product of two exponential functions. Multilying exponentials means adding t...

22 days ago | 1

| accepted

Answered

How to copy colormap from an existing image

HI Alexei I copied the image you provided as a jpeg, used datatips to find coordinate points at the top and bottom of the color...

How to copy colormap from an existing image

HI Alexei I copied the image you provided as a jpeg, used datatips to find coordinate points at the top and bottom of the color...

23 days ago | 0

| accepted

Answered

Taking an average of every n elements of one column

Hi Tony, a = rand(144,73,551); b = squeeze(a(:,3,:)); % take all the third columns c = mean(reshape(b,12,[])...

Taking an average of every n elements of one column

Hi Tony, a = rand(144,73,551); b = squeeze(a(:,3,:)); % take all the third columns c = mean(reshape(b,12,[])...

24 days ago | 0

Answered

Integration of a vector with hyperbolic function

Hi Sunit, Thanks for annotating the code and providing the expressions as comments. The key here is with the C1 coefficient...

Integration of a vector with hyperbolic function

Hi Sunit, Thanks for annotating the code and providing the expressions as comments. The key here is with the C1 coefficient...

24 days ago | 1

| accepted

Answered

After the FFT(Frequency-Amplitude) of the seismic wave(Time-Acceleration), I want to reconstruct the seismic wave(Time-Acceleration) by IFFT again.

Hello haeyeon, A couple of things here. First of all, you are using nextpow2 to go from what looks like 10001 points to 16384....

After the FFT(Frequency-Amplitude) of the seismic wave(Time-Acceleration), I want to reconstruct the seismic wave(Time-Acceleration) by IFFT again.

Hello haeyeon, A couple of things here. First of all, you are using nextpow2 to go from what looks like 10001 points to 16384....

24 days ago | 0

Answered

How do you do a radial Fourier transform in MATLAB?

Hi S, here is one way. First of all, the transform pair is q*F(q) = Int r*F(r) sin(q*r) dr r*F(r) = (1/(2*pi))*In...

How do you do a radial Fourier transform in MATLAB?

Hi S, here is one way. First of all, the transform pair is q*F(q) = Int r*F(r) sin(q*r) dr r*F(r) = (1/(2*pi))*In...

24 days ago | 0

| accepted

Answered

FFT and PSD - normalize values

Hi John, This concerns fft only; psd is a different animal. For a continuous oscillation, most people do not seem to be concer...

FFT and PSD - normalize values

Hi John, This concerns fft only; psd is a different animal. For a continuous oscillation, most people do not seem to be concer...

25 days ago | 0

| accepted

Answered

Problem with using symbolic integration

Hello Yasho, For any reasonable q, integrating from l to u gives F = 1 by definition of the beta function. When q is an intege...

Problem with using symbolic integration

Hello Yasho, For any reasonable q, integrating from l to u gives F = 1 by definition of the beta function. When q is an intege...

26 days ago | 1

| accepted

Answered

Time of sparse matrix components allocation

Hi reza, with sparse matrices you want to build up a set of indices to use in the first two inputs, in order to make a single c...

Time of sparse matrix components allocation

Hi reza, with sparse matrices you want to build up a set of indices to use in the first two inputs, in order to make a single c...

29 days ago | 0

| accepted

Answered

Matrix differential equations, correct answer?

Hi Sara, this plot figure(1) tvec = 0:.01:6; reliability_d = double(subs(reliability,t,tvec)); rel_d = double(subs(rel,t,tv...

Matrix differential equations, correct answer?

Hi Sara, this plot figure(1) tvec = 0:.01:6; reliability_d = double(subs(reliability,t,tvec)); rel_d = double(subs(rel,t,tv...

30 days ago | 1

| accepted

Answered

Plotting a section of a hemisphere using parametric equations

Hi Marcus theta=[0:0.01:1]*2*pi; ensures that the value of 2*pi is reached.

Plotting a section of a hemisphere using parametric equations

Hi Marcus theta=[0:0.01:1]*2*pi; ensures that the value of 2*pi is reached.

1 month ago | 0

| accepted

Answered

Trying to solve time of charge of supercapacitor with ode45

Hello Isaac It seems easier to do this as two first order equations for the node voltages V1 and V2 rather than go to a second ...

Trying to solve time of charge of supercapacitor with ode45

Hello Isaac It seems easier to do this as two first order equations for the node voltages V1 and V2 rather than go to a second ...

1 month ago | 0

| accepted

Answered

How to use one ode45 to solve another?

Hi Carlos, you can toss them all in together, with g(1) = y(4) and g(2) = y(5). That way y(1) is available in context. t0=0; ...

How to use one ode45 to solve another?

Hi Carlos, you can toss them all in together, with g(1) = y(4) and g(2) = y(5). That way y(1) is available in context. t0=0; ...

1 month ago | 0

| accepted