How to plot the exponentional function in matlab

Hello everyone

I want to plot this expression of probability in matlab y=exp(-(K-1)) in function of P[dB]. How can I do it? Please i need help.

I tried with this code but it doesn't go.

function y = Swb(K,p)
  K=4;
  y= exp(-(K-1));
end

Answer 1

[Image Analyst]

You need to use the plot() function.

[Birdman]

But he wants the psd of the function. Therefore doesn't he have to use pwelch?

[Image Analyst]

Where does he say he wants the PSD? If he did, then yes, he'd use pwelch(). But I see him saying "I want to plot this expression...." and for that you'd use plot(). Of course his expression is just a single number since y = exp(-(K-1)) = exp(-(4-1)) = exp(-3) = 0.04978706.

I think he needs to read this link

[Birdman]

I think you miss this part :

...in function of P[dB].

Answer 2

[lakom Mariem]

Thanks all me,I want to reproduce this figure.For every single curve ,there is its own expression of probability.For example, for "SW" the expression of probability is Psw = exp(-(K-1)).Please can anyone help me how can i do it if you please and thanks in advance.

[Image Analyst]

WHAT figure? You forgot to attach it and you forgot to attach any data, like what is the p you send in when you call

y = Swb(K,p);

And why do you send in K when you immediately overwrite it with a value of 4?

[lakom Mariem]

@Image Analyst : thank you. About P it represents the power. honestly i'm new beginner at matlab and still don't know how to plot a curve..I want to plot the expression of probability (Prob = exp(-(K-1)) ) in function of P(P is the power [dB]).Please i need your help if you can.I tried with this code but i think it's wrong. function y = Swb(K,p)

K=4;

    y= exp(-(K-1));

end

[Image Analyst]

Do you mean like this:

p = linspace(0, 50, 500);
% Compute and plot for K=1
y = Swb(1, p);
subplot(2, 2, 1);
semilogy(p, y, 'LineWidth', 2);
grid on;
% Compute and plot for K=2
y = Swb(2, p);
subplot(2, 2, 2);
semilogy(p, y, 'LineWidth', 2);
grid on;
% Compute and plot for K=3
y = Swb(3, p);
subplot(2, 2, 3);
semilogy(p, y, 'LineWidth', 2);
grid on;
% Compute and plot for K=4
y = Swb(4, p);
subplot(2, 2, 4);
semilogy(p, y, 'LineWidth', 2);
grid on;

function y = Swb(K,p)
y = exp(-(K-1) * p);
end

[lakom Mariem]

thanks a lot. But I want just to know why do you modified this expression y=exp(-(K-1) * p); normally ti is just y=exp(-(K-1); why do you multiplied it by p (*p) ??

Thanks

[Image Analyst]

If K is just a single number, like 4, then exp(-(K-1)) is just exp(-3), which is just 0.0497870683678639, not a whole curve. What would you have as the x coordinate?

[lakom Mariem]

Ok I understand.thanks a lot