bandwidth from 2D array

Hello,i have a 2D array of numbers, i need to take the peak value which always located at the same X=0 point and subtracts 3 and find the two points(positive X-axes and negative X axes) in this table which are the closest to these values.

for example if my value at x=0 is 7 then i need to find the two places int the Y axes which are closest to 4.

if if we have (-30,4.1) and (+32,4.3) then the bandwidth 30+32 is 62 i thought of running two parallel "for" one for positive axes one for negative axes and taking the closest point on each side by checking iteratively.

is there an easier way?

Thanks

[KSSV]

Giving the data would help us to help you..

Answer 1

[KSSV]

clc; clear all ;
y = 2*sin(linspace(0,pi))' ;
x = [1:length(y)]' ;
p = [x y] ;
%%get maximum 
[val,idx] = max(y) ;
% substract and add a value 
dw = 0.2 ; % value to be substracted 
y0 = val-dw ;
% get the nearest values 
id = find(abs(y-y0)-dw <= 10^-3) ;
idx0 = id(1) ; idx1 = id(end) ;
% required points 
p0 = [x(idx0) y(idx0)] ;
p1 = [x(idx1) y(idx1)] ;
% Bandwidth 
BW = abs(x(idx0)-x(idx1)) ;
% plot
figure 
hold on
plot(x,y,'r') ;
plot(x(idx), y(idx),'Or') 
plot(p0(1),p0(2),'*g')
plot(p1(1),p1(2),'*b')