Community Profile # Alan Stevens

Last seen: Today Active since 2020

#### Statistics

• • • • #### Content Feed

View by

Solving first order ODE with initial conditions and symbolic function
You can do it numerically as follows: % input parameters Tinf=70+273.15; Ti=20+273.15; d=15e-2; r=d/2; cdepth=10/1100; Tf...

3 days ago | 0

can someone help me to analyze this program? How does the flowchart look like?
Perhaps this will help: %radiasi benda hitam % constants h=6.626e-34; c=3e8; k=1.38066e-23; % range of values lambda ...

6 days ago | 0

Error using surf (line 71) Data dimensions must agree
More like this? for it=1:2 for jt=1:3 zt(it,jt)=it+(jt-1); end end [x,y] = meshgrid(1:3,1:2); figure; surf(x...

6 days ago | 1

How to find Basins of attraction for the Halley method?
Don'tforget the dot multiply: f = @(z) z.^3 +1; df = @(z) 3*z.^2; ddf=@(z) 6*z; % its roots r1 = -1; r2 = 1/2 + 1i*...

1 month ago | 0

| accepted

"Invalid use of operator." doesn't go even after trying various solutions :(
Why nor just use Matlab's inbuilt cart2pol function?

1 month ago | 0

Heat equation using Boundary condition
function statements of this form (i.e. functions eq1, initial and ba) need to go at the end of the script, not the start.

2 months ago | 0

A for loop that will run until a specific mathematical value is found
You could try replacing the "for i = 2:10 " loop by something like nports = 1; while Q(i)<Qdesired nports = nports ...

2 months ago | 0

| accepted

How to plot all figures in only one plot?
Here's one simple way: x=-pi:0.1:pi; c=-6:5; figure hold on for i=1:length(c) y=c(i)*x.^(2)+4*x+2; plot(x,y) end...

3 months ago | 0

| accepted

Error in Hermite Polynomial
In line for j = 0:i-1 you have j starting at zero. Matlab's indices start at 1, so the following line should have X(j+1) not ...

4 months ago | 0

Matlab code not computing
The use of square brackets in the scatter function is not the only problem! Are you looking for something like this? p=-1; z=...

5 months ago | 0

| accepted

how to plot the path of circular beam oscillation welding?
Like this? A=1; f=50; vf=0.02; time = linspace(0,100,500); x0 = vf*time; theta = 2*pi*f*time; x=A*cos(theta)+x0; y=A*sin...

5 months ago | 0

how to change the direction of the airfoil
Change contourf(real(J),imag(J),imag(f),v2); %%%%% fill(real(zair),imag(zair),'k') to contourf(-real(J),imag(J),imag(f),v2);...

5 months ago | 0

| accepted

How to use 5 function coupled each other using ODE45? it is possible?
Better like this: MM0 = [10, 0, 0, 0, 0]; tspan = [0 100]; [t, MM] = ode15s(@mymode, tspan,MM0); M1 = MM(:,1); M2 = MM(:...

6 months ago | 0

| accepted

convert a column matrix with many rows into multiple column of equal rows
Try the reshape function.

6 months ago | 0

"Not enough Imput arguments" ERROR
You haven't included J as an input argument to function Feedback_Ven_STEP.

6 months ago | 0

| accepted

Using polyfit in two arrays to detrend data.
polyfit just returns the coefficients of the polynomial. You need to use them in polyval to calculate data values.

6 months ago | 2

Implicit solution using pdepe 1D advection diffusion reaction equation
I think you've overcomplicated the situation! Should be more like the following (which you should check very carefully, as I di...

6 months ago | 0

I want to plot the vector field on F=x i+ j
Do you mean like this? [x,y] = meshgrid(-3:.15:3,-3:.15:3); Fx = x; Fy = ones(size(y)); %%%%%%%%%%% figure; quiver(x,y,Fx,F...

6 months ago | 0

| accepted

i have two set of data for temperature measurements which vary depends on each other. the variation may be divided into three portions. how can we seperate these portions
Here's a possible way (assumes the data is already in the workspace): dT2 = gradient(T2); minval = min(dT2(Time<2.5)); ix = f...

6 months ago | 0

How to surf very small values keeping the same ratio?
Multiply them all by 1e4.

6 months ago | 0

whats preventing my code from generating the proper results
I don't know anythng about the physics of your scenario, but are you sure you are calculating NLOS_LOWER_BOUND correctly? The f...

6 months ago | 0

Finding the optimal solution for a data with two variables
Here's a possible approach (I've used relative errors as the values of the two columns are an order of magnitude different): % ...

6 months ago | 0

| accepted

Using loop to sum value of an array and summation
Here's one way: J=[1 2 3 4 5 6 1 2 3 4 5 6]; step = 3; ix = 1:step:numel(J); for i = 1:numel(ix) p(i) = sum(J(ix(i)...

6 months ago | 1

| accepted

Solving a system of inequalities using an eigenfunction and if, else.
Your function needs to be more like this, for example. Set values of x outside the function, call the function with these value...

6 months ago | 0

| accepted

Почему появилась ошибка?
Seems overcomplicated for a numerical solution! How about simply f = @(x) x - 5 - 1/3*cos(2*x+1) + 2*x./(2+x.^2); g = @(x) x ...

6 months ago | 0

How to write 2D heat conduction exact solution for Inf n?
Your term sinh(n*pi*x/L) should be sin(n*pi*x/L). See the following code (which can be made more efficient!): L = 1; H = 2; ...

6 months ago | 1

| accepted

Help with Riccati equation
You haven't defined B (in the function definition)

6 months ago | 0