Answered

Analizing the charges and discharges of a capacitor conected to a square wave voltage source

Hello Virginia, As you progress along the square wave, each time you get to a new half cycle there is of course a new applied v...

Analizing the charges and discharges of a capacitor conected to a square wave voltage source

Hello Virginia, As you progress along the square wave, each time you get to a new half cycle there is of course a new applied v...

2 months ago | 0

| accepted

Answered

How to solve a set of coupled odes that depend on derivatives

HI charlie, dx4' depends on dx2' and dx3' explicitly. But since dOmega_e_dz and dV_e_dz are also in the expression for dx4', d...

How to solve a set of coupled odes that depend on derivatives

HI charlie, dx4' depends on dx2' and dx3' explicitly. But since dOmega_e_dz and dV_e_dz are also in the expression for dx4', d...

2 months ago | 0

Answered

Issue with gammainc(x,a) for small x and larger a

Hi John, Matlab does not appear to have a symbolics version of the incomplete gamma function, but it's still possible to make p...

Issue with gammainc(x,a) for small x and larger a

Hi John, Matlab does not appear to have a symbolics version of the incomplete gamma function, but it's still possible to make p...

2 months ago | 0

Answered

im using 'dsolve' for 2nd ode with dirac function but matlab returns 1/2 of constant

Hi Song-Ha Your statement " the answer should be [constant] *exp(-0.4607 * t) * sin(3.0003*t) " is missing a very important f...

im using 'dsolve' for 2nd ode with dirac function but matlab returns 1/2 of constant

Hi Song-Ha Your statement " the answer should be [constant] *exp(-0.4607 * t) * sin(3.0003*t) " is missing a very important f...

2 months ago | 0

Answered

Hypergeometric Function in Matlab

Hello PM, The variable l does not come out so well in this font so I'll call it q instead. SInce both -q and -n are negative, ...

Hypergeometric Function in Matlab

Hello PM, The variable l does not come out so well in this font so I'll call it q instead. SInce both -q and -n are negative, ...

2 months ago | 0

| accepted

Answered

ODE45 Code Application

Hi James, [t,U] = ode45(@Velocity, [0, 20], .001); plot(t,U) function Udot = Velocity(t,U) M = 100/6*pi*0.04^3; g=9.8; A...

ODE45 Code Application

Hi James, [t,U] = ode45(@Velocity, [0, 20], .001); plot(t,U) function Udot = Velocity(t,U) M = 100/6*pi*0.04^3; g=9.8; A...

2 months ago | 1

| accepted

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...

2 months ago | 1

| accepted

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...

2 months ago | 0

| accepted

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...

2 months 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...

2 months 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

2 months ago | 0

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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...

2 months 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 ...

2 months 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...

2 months 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...

2 months 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...

2 months ago | 0

| accepted

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...

3 months 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...

3 months 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...

3 months 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 ...

3 months 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...

3 months 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...

3 months 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...

3 months 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...

3 months 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...

3 months 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,[])...

3 months 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...

3 months 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....

3 months 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...

3 months 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...

3 months ago | 0

| accepted