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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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What is the problem for the following matlab code for drawing contour plots of R0 against two parameters?
alpha= 1.0*0.0241; beta=0.001936 ; gamma=0.0020255; T=23.3; T0=23; mu_ref = 0.0017; mu1=0.039 ;mu2=0.002894; L=8; L0=8 ; delta...

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fmincon is not working
You must define F = @(x) fun(x(1),x(2)) and pass "F" instead of "fun" to fminunc.

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How to integrate a complicated function?
https://www.wolframalpha.com/input?i=integration&assumption=%7B%22C%22%2C+%22integration%22%7D+-%3E+%7B%22Calculator%22%7D&assum...

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Function optimization with some conditions conditions
The dimensions would be correct if you use b = [b1;b2.';b3.']; instead of b = [b1;b2;b3]; but you'd better post the problem ...

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How do you go about guessing for fitting parameter initializations?
This is a linear fitting problem for which you don't need initial guesses for the parameters: Data = [0.006 334 0.011 276 ...

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How to solve a boundary value problem x"+x'=1, x(0)=1, x(1)=2 , with an impulse condition x(i/3+)=2*x(i/3)+1, x'(i/3+)=3*x'(i/3)-1;
syms t x1(t) x2(t) eqn1 = diff(x1,t,2) + diff(x1,t) == 1; Dx1 = diff(x1,t); eqn2 = diff(x2,t,2) + diff(x2,t) == 1; Dx2 = dif...

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Error: In an assignment A(:) = B, the number of elements in A and B must be the same.
w(i)=w; This line of code makes no sense. You want to assign a vector w to a scalar w(i).

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solving complex matrix with symbolic variables
syms a b c d e f g h k real z1=-30j; z2=0.08+0.40j; z3=-35j; z4=0.10+0.50j; z5=0.10+0.50j; z6=-25j; z7=0.30j; p1=a; p...

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Kindly help me out with this code. its urgent please .thanks
The trigonometric functions sin, cos for an argument x are invoked as sin(x), cos(x),... If they have an exponent, they are eit...

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How can I create a spline with conditions on the middle?
% Set up the problem with 16 conditions for 16 spline coefficients syms a [4,1] syms b [4,1] syms c [4,1] syms d [4,1] ...

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Research of inflexion point - Index exceeds the number of array elements.
You forgot to initialize x as x = [] in the second example.

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Fit a statistical distribution to truncated data
Why should it be justified to fit a dataset of a truncated normal by a normal distribution ? pd_fit_trunc = fitdist(data_trunc,...

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Roots of an equation when two parameters are changed
"num" is a polynomial of degree 7 in M. Thus it has seven roots. But your code only gives one of these seven. So I hope you get ...

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How can i find the roots of the complex equation?
You can get an analytical solution if you substitute y = z^2: syms y p = y^4 + (10548593400*y^3)/42679 + (33343133111071335000...

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How to solve delay differential equations with computed history (not constant)
Save the results of the non-delayed ode in arrays T and Y, create an interpolation function fun_history = @(t) interp1(T,Y,t) ...

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use of fminimax solver in matlab for optimization
z seems to be a constant in your objective function. Thus it doesn't influence the result of the optimization and doesn't need t...

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Arrhenius model fitting using fminsearch
Your model function σ(T) = σ_ref * exp(-Ea/(kT)) does not have a maximum. Thus it is not suited to reflect your measurement data...

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maximization with fmincon which of the two codes provided do the correct job
I suggest using a function instead of a function handle. I compared it with your implementation and random matrices for W and R...

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Arrhenius model fitting using fminsearch
Imagine you get Ea = 3 and k = 6 in one run and Ea = 12 and k = 24 in a second run. Both solutions give the same quality of fitt...

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Assign a value to a matrix element defined as a variable
prop = @(x)[[x(1)*ones(11,1);x(2)*ones(12,1)],[x(3)*ones(11,1);x(4)*ones(12,1)],zeros(23,1),zeros(23,1)]; prop([1 2 3 4])

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can find regression and curve fit for given equation
Since your equation can be rearranged as dy/dx = 1/c * log((m-a)/b) your model assumes that dy/dx is equal to a constant that ...

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