How can I plot the function of Resistor Voltage Vr

In this situation, I am assuming frequency f is a unknown varible ( just like variable x). I want to plot a graph of function Vr ( resistor voltage) in the range frequency of [0, 4e6] where Vr = (Vo*R)/Z

clear all

clc

% Define the value of R,C,L

R = 1000;

C = 120e-12;

L = 470e-6;

f = 4e6;

V0 = 220;

syms f

% Define the function of Resistor Voltage Vr

Vr = (V0*R)/sqrt((R^2)+(2*pi*f*L - 1/2*pi*f*C)^2);

fplot(@(f) Vr,[0 4e6])

Answer 1

[Star Strider]

You are almost there. Define ‘f’ as an anonymous function, vectorise it, and plot:

% Define the value of R,C,L 
R = 1000;
C = 120e-12;
L = 470e-6;
f = 4e6;
V0 = 220;

% Define the function of Resistor Voltage Vr
Vr = @(f) (V0*R)./sqrt((R^2)+(2*pi*f*L - 1/2*pi*f*C).^2);
fplot(Vr,[0 4e6])

That worked when I ran it. (The Symbolic Math Toolbox ios not required here.)

From my experience, an extra set of parentheses iw likelly necessary, so consider this:

Vr = @(f) (V0*R)./sqrt((R^2)+(2*pi*f*L - 1./(2*pi*f*C)).^2);

instead.

[Phillip Phuc]

Thank you so much Star Strider, it ran perfectly. And may I know what does the dot "." mean ?

[Star Strider]

As always, my pleasure!

The dot operators (with multiplication, division, and exponentiation) indicate element-wise or array operations. See: Array vs. Matrix Operations for a full discussion. (The exception is the transpose operator (') that ordinarilly does a complex-conjuage transpose although (.') does a simple transpose with the conjugate operation.)

Answer 2

[Richard Duran]

Write a function called voltage that computes the voltages at different junctions.help please

[Micheal Omojola]

Here is the solution to your question:

function [a,b] = lin_reg(x,y)
len = length(x);
aug = [x' ones(len,1)];
res = aug\y';
a = res(1);
b = res(2);
end