how to plot y=|x| function without using abs,

hi im trying to plot two functions the first y=|x| the second y=|x+4|-|x^2-7| without abs func but with for and if please help thanks

[James Tursa]

What have you done so far? What specific problems are you having with your code?

Answer 1

[bio lim]

Well you have to find the regions where your values of y are positive and negative. Here is an example of y = |x|.

x = -100:100;
for i = 1:length(x)
    if x(i)<0
        y(i) = -x(i);
    else y(i) = x(i);
    end
end

[rivaldo rivaldo]

thanks now i need to plot y=|x+4|-|x^2-7| in -10:0.01:10 region without abs

[bio lim]

Well, as James Tursa wrote, you have to show us what you have done so far.

[rivaldo rivaldo]

clear all;close all;clc

x = -10:0.01:10;

for i = 1:length(x)

if x(i)+4>0

 y(i)=-x(i)+4;
    else y(i) = -x(i)-4;
    end
    for j=1:length(x)
        if x(j).^2+7>0
            g(j)=x(i).^2+7;
        else g(j)=-x(i).^2-7;
        end

end

plot(x,y)

hold on

plot(x,g)

[bio lim]

x = -10:0.01:10;

% let's call a = |x+4|
%            b = |x^2 - 7|

for i = 1:length(x)
    if (x(i)+4<0)
        a(i) = -(x(i)+4);
    else a(i) = x(i)+4;
    end
end

for i = 1:length(x)
    if (x(i)^2-7<0)
        b(i) = -(x(i)^2 -7);
    else b(i) = x(i)^2 -7;
    end
end
y = a - b;