MATLAB: Find the value x

exphomeworklocal minimum

y = x ^ e – e ^ x is [0 5] when x^e=e^x

Best Answer

>> [x,fval]=fminbnd(@(x) abs(exp(x)-x^exp(1)),0,5)
x =
    2.7183
fval =
   4.4743e-11

Related Solutions

MATLAB: Does the programm do not run the script and continues to get unexpected expression

You cannot run your assignments and commands in any order. You have to write your script so that MATLAB has functions and arguments in its workspace in the order it needs for you to state them.

With a bit of editing of the order of the statements in your code, this works:

x = linspace (0,10);
x = 0:0.5:10;
y = 2-10*x.*exp(-.8*x);
plot (x, y); grid on;
x = 0
y = 2-10*x.*exp(-.8*x)
f = @(x) 2-10*x.*exp(-.8*x)
[xr fx] = fzero(f, 0)
[xrr fx] = fzero(f, 4)
[xmin, fmin]=fminbnd(f,1,2)
%PART 2
% line12>>
func= @(x,y) 2+x-y+2*x.^2+2*x.*y+y.^2;
[xgrid, ygrid]=meshgrid(-2:0.1:0,0:0.1:3);
subplot(1,2,2) 
surf(xgrid,ygrid,func(xgrid,ygrid))
subplot(1,2,1)
contour(xgrid,ygrid,func(xgrid,ygrid))
subplot(1,2,2); surf(xgrid, ygrid, func(xgrid,ygrid))
f = @(x) 2+x(1)-x(2)+2*x(1)^2+2*x(1)*x(2)+x(2)^2
[x, fval]=fminsearch(f,[-.5, 0.5])

I leave it to you to determine if it produces the results you want.

MATLAB: Fsolve not enough input arguments

You need to supply System() as a function handle to fsolve(). The way you have written it, Matlab thinks you want to simply call the function System(), and supply the result to fsolve().

As far as I know, the script itself should not execute because you can't define functions within scripts.

clc, clear
x0 = [1, 1, 1, 1,1];
Coefficients = fsolve(@(x)System(x), x0)

In a separate file (also, it looks like your function "System" will also not return an output, so need to change the output name):

function F = System(x)
F = nan(1,6);
F(1) = x(1)*[exp(x(4)/x(2)) - exp(-x(4)/x(3))] - 0.9;
F(2) = x(1)*[exp(-(x(4)-0.6*1.2e-6)/x(2)) - exp(-(x(4)-0.6*1.2e-6)/x(3))] - 0.3;
F(3) = x(1)*[exp(-50e-6/x(2)) - exp(50e-6/x(3))] - 0.5;
F(4) = x(1)*[exp(-x(5)/x(2)) - exp(-x(5)/x(3))] - 1;
F(5) = -x(1)/x(2)*exp(-x(5)/x(2)) + x(1)/x(3)*exp(-x(5)/x(3));
F(6) = 30e3*x(1)*(exp(-x(4)/x(2)-exp(-x(4)/x(3)))) - 30e3*x(1)*(exp(-(x(4)-0.6*1.2e-6)/x(2))-exp(-(x(4)-0.6*1.2e-6)/x(3)));
end

I would also ask about the math problem, which looks over-specified...5 unknowns in 6 equations

Best Answer

Related Solutions

MATLAB: Does the programm do not run the script and continues to get unexpected expression

MATLAB: Fsolve not enough input arguments

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