MATLAB: How can i solve this problem and plotting

equationnonlinear

x=1:1:50;
plot x,a grap?

Best Answer

I assume you want to find the values of a that make the integral = 75, for all values of x. if so, then the following should do it:

x = 1:50;
aguess = 50;
for i = 1:50
    a(i) = fzero(@(a) fn(a,x(i)),aguess);
    aguess = a(i);
end
plot(x,a,'o'),grid
xlabel('x'),ylabel('a')
function z = fn(a,x)
        f = @(x) sqrt(1+(2*a*x).^2);
        z = integral(f,0,x)-75;
end

Note that the a's found from the above are positive, but the negative equivalents would also work, because a is squared in the integral.

Related Solutions

MATLAB: Having trouble plotting

Perhaps you need to use ./ and .^ instead of / and ^.

Try this:

% Variables
Cd = 0;
Cd0 = 0.018;
W = 670; %kN
AR = 6.5;
A = 150; %m^2
p = 0.413; %kg/m^3
Cl = 0;
Fd = 0;
v = 100;
% Formulas
% Cl = (2 * W) / (p * v ^ 2 * A);
% Cd = Cd0 + (Cl ^ 2 / (pi * AR));
% Fd = W * (Cd / Cl);
v = linspace(100, 1000);
Cl = (2 * W) ./ (p * v .^ 2 * A); 
hold on;
Cd = Cd0 + (Cl .^ 2 / (pi * AR));
Fd = W * (Cd ./ Cl);
Fd2 = Fd ./ v;
plot(v, Fd2);

MATLAB: How to plot an expression which contains integral

This code will numerically integrate the expression, and plot real and imaginary part.

exponentTerm1 = @(x_) 2-x_.^2;
exponentTerm2 = @(x_) cos(pi*x_/2)./(2-x_.^2);
exponent = @(x) 1i*integral(exponentTerm1, -1, x) + integral(exponentTerm2, -1, x);
f = @(x) exp(exponent(x));
x = -1:0.1:sqrt(2);
y = arrayfun(f, x);
subplot(211)
plot(x, real(y));
title('real')
subplot(212)
plot(x, imag(y));
title('imaginary')

Best Answer

Related Solutions

MATLAB: Having trouble plotting

MATLAB: How to plot an expression which contains integral

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