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Visualizing 2D Slices of a 3D Shape Subject to 3D Heat Equation and Boundary Conditions
I have no experience with the PDE toolbox, but it seems from the error message that you defined a stationary, not a time-depende...

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Trying to find a solution for nonlinear ODE
The variables are ordered as [y(1) y(2) y(3) y(4)] = [p dp/dx q dq/dx]. You will have to add the boundary condition part. syms...

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problem in for loop not working in fixed point iteration while loop
Maybe like this ? clear all load('results.mat') N_pr = 99; P_sat = Pb; P_abandon = 1700; delh_pr = (P_sat-P_abandon)/N_pr;...

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Plotting the 3D Heat Equation in 2D Slices
Your implementation of Explicit Euler looks correct. If you want larger time steps and faster performance, use an ODE solver li...

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How to get the available solution of the singular matrix equations?
The system cannot be solved with equality because rank(A) = 68 while rank([A,b]) = 69. You can only try to find a vector x that...

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please help me modify the code i want to simulate the temperature profile distributed along the height of the adsorption column
If you don't want to save the temperatures for all time steps, you need at least two arrays T_old and T_new such that your advan...

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Fmincon finds different solutions for optimization problem in dependance of initial values
It's not unusual that the solution for optimization problems depends on the initial guesses for the optimization variables. If...

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Integral and inverse integral
MATLAB is not able to find the inverse: syms x Sigma= 1; Mu=5; PDF_Norm=exp(-0.5.*((x-Mu)/Sigma).^2)/(Sigma*sqrt(2*pi)); a...

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Euler's identity with angle in degrees
a = 30; exp(deg2rad(a)*1i) exp(a*pi/180*1i)

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Least squares linear regression with constraints
You made a mistake in computing the correct coefficients (see below). clear all close all x11 = [0.091, 0.068, 0.086, 0.091, 0...

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Nonlinear regression with two variables
I don't know your inputs, but theoretically, it works: X = rand(50,2); Y = rand(50,1); % Define the model function model = @...

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Accessing local variables in a function.
By defining them as output variables function [x,y] = drawHexagon(sideLength, centerX, centerY) and calling the function as [...

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How to solve a system of distributed delay equations?
As a start, you could define three delays, namely delay(1) = tau-gamma, delay(2) = tau and delay(3) = tau+gamma, and approximate...

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How to use Jacobian option of odeset for ode15i while solving DAEs?
syms x1(t) x2(t) x3(t) m l g c; % DAE system eqn1 = diff(x1(t),t)-x3(t)==0; eqn2 = diff(x3(t),t)*sin(x1(t))-x2(t)*cos(x1(t)...

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Symbolic simplify get wrong result
(a*b)^1/3 = (a*b)/3, not = (a*b)^(1/3)

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Solving a complicated non-linear equation in Simulink
With suitable constants c1,...,c6 and substituting x = sin(sigma_A^EC), your equation can be written as c1*(x^2-c2) - c3*(x*c4-...

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What is the main difference between gradient command and diff comand
gradient: 5-1,(10-1)/2,(17-5)/2,(30-10)/2,30-17 diff: 5-1,10-5,17-10,30-17 Both are approximations to the slope of x if the sp...

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Symbolically solve non-linear differential equation
You don't need to solve the equation symbolically. Just solve simultaneously the two differential equations %db2/dt=b2*(c2*(1-...

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Solving system of four equations
syms e1 e2 e3 e4 for i=1:25 eq1=((nco+v3*e1+v22*e2+v41*e4)^2*(nh2+v4*e1+v24*e2+v33*e3)^2)-(k(i)*(n0+v*e1+v03*e3+v04*e4)^2*...

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How to output simple linear regression confidence limits for new values of independent variable.
My guess is that your linear model has two independent variables. That's why you had to supply a two-column vector of new X-va...

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Solving Matrix Equations With Unknown at Both Sides
syms T1 T3 F2 eqns = [1 -0.5 4;-0.5 2 0; 4 0 3]*[T1;0;T3]==[4;F2;5]; solve(eqns)

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How to plot xy, yz and xz plane contour with integration matrix equation
clear all close all clc %Constant rho = 4420; %kg/m^3 Cp = 550; %J/kg?K T0 = 303.15; %K A = 0...

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How can I solve non-linear equations with more equations than unknown variables using objective functions such as nonlinear least square (lsqnonlin)?
rng("default") P1 = rand(3,1); P2 = rand(3,1); M1 = rand(3,4); M2 = rand(3,4); x0 = [1 1 1 1 1]; fun1 = @(x) norm(P1-M1*[x...

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Calculation of quadruple integral in combination with summation
z_array = 2:3; Z_array = 4:5; r1 = 2; r2 = 3; R1 = 5; R2 = 7; for i = 1:numel(z_array) z = z_array(i); for j = 1:num...

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Problem about the ode45 time steps?
You specify the times when you want ODE45 to output the solution in the array "tspan". This array is not used by ODE45 to deduc...

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Changing y tick values interval
fun = @(x)x; x = -4000:360; y = fun(x); plot(x,y) yticks(fliplr(360:-360:-4000))

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I have calculated 4 standard deviation values for each row of a 4x3 matrix. How to convert these 4 values into a single standard deviation value for the whole matrix?
Not possible. Use std(a(:)) instead.

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How to calculate a double integral with a subfunction?
Use obj = integral2(@(theta,phi)arrayfun(@(x,y)pattern_element(f0,x,y,L,W),theta,phi),0, 2*pi,0, 2*pi) instead of obj=integra...

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It always gives the error of "Empty sym: 0-by-1"
The result is correct: You have 26 equations of the form 1800 - c(i)*Fe = 0 for one variable Fe to be solved for, but 26 dif...

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error: matrix dimensions must agree
K_a in your function definition is a scalar. Thus you have to change x0 to be a scalar, too. clc close all clear background...

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