How to find the closest values (positive and negative) to the line when X is zero?

Hi,

I am trying to find the closest two points (positive and negative) when x is zero, I tried with interp1 and find but it didn't work.

Something similar like the image.

This is my code

Thanks for the help

%Data 
load Data

%Create line plot 

x = V;
y = J; 
%plot(x,y,'b-','LineWidth',5);
plot(x,y,'-o','MarkerIndices',1:19:length(y))
hold on


%Label the axes and add a title 

xlabel('Voltage V')
ylabel('density current mA/cm2')
title('J-V curve ')

% Set axis start from origin 


axis([-0.06 0.7 -0.001 0.008])


%yDesired = interp1(x,y,0);
%Minimum x value for positive y 

%Y line 

x1 = [0 0];
y1 = [0 0.1];
line(x1,y1,'Color','red','LineStyle','--')


%X line 

x2 = [0 0.7];
y2 = [0 0];
line(x2,y2,'Color','red','LineStyle','--')


%find the value when x=0

y=interp1(x,y,0)

Answer 1

[Matt J]

load Data

%Create line plot 
[x,is] = sort(V);
y = J(is); 


in=find(x<0,1,'last');
ip=find(x>0,1,'first');

[xn,yn, xp,yp]=deal(x(in),y(in), x(ip), y(ip));

plot(x,y,'.',xn,yn,'o',xp,yp,'o');

axis([-0.0056    0.0059    0.0060    0.0063])

[Valentin Augusto Simbron Mckay]

Thanks for the help