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

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rivaldo rivaldo on 3 Dec 2016
Commented: bio lim on 3 Dec 2016
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 on 3 Dec 2016
What have you done so far? What specific problems are you having with your code?

bio lim on 3 Dec 2016
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 on 3 Dec 2016
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 on 3 Dec 2016
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;