how to convert a wave form into 2D matrix form using for loop?

my code is here
%%STEP FIRST (wave form)
clc;
clear all;
Imax=0.8;
Imin=0.2;
Im=Imax-Imin;
T = 20;
s1= @(x) ((2*Im*x/T)+Imin+Im/2).*(0<=x & x<=T/4) +((-2*Im*x/T)+Imin+3*Im/2).*(T/4<=x & x<=3*T/4)+((2*Im*x/T)+Imin-3*Im/2).*(3*T/4<=x & x<=T);
x = linspace(0, 20);
I1 = s1(x);
figure(1),plot(x,I1)
% second step (2D matrix image)
m=1000;
n=1000;
for i=1:m
    for j=1:n
        s1= @(x) ((2*Im*x/T)+Imin+Im/2).*(0<=x & x<=T/4) +((-2*Im*x/T)+Imin+3*Im/2).*(T/4<=x & x<=3*T/4)+((2*Im*x/T)+Imin-3*Im/2).*(3*T/4<=x & x<=T);
        I(i,j)=s1*(j/n+i/m);
    end

end
imshow(I,[]);

second step is not working, where is wrong? please help please find attachment

Answer 1

[KSSV]

clc;
clear all;
Imax=0.8;
Imin=0.2;
Im=Imax-Imin;
T = 20;
s1= @(x) ((2*Im*x/T)+Imin+Im/2).*(0<=x & x<=T/4) +((-2*Im*x/T)+Imin+3*Im/2).*(T/4<=x & x<=3*T/4)+((2*Im*x/T)+Imin-3*Im/2).*(3*T/4<=x & x<=T);
x = linspace(0, 20);
I1 = s1(x);
figure(1),plot(x,I1)
% second step (2D matrix image)
m=1000;
n=1000;
I = zeros(m,n) ;
for i=1:m
    for j=1:n
        s1= @(x) ((2*Im*x/T)+Imin+Im/2).*(0<=x & x<=T/4) +((-2*Im*x/T)+Imin+3*Im/2).*(T/4<=x & x<=3*T/4)+((2*Im*x/T)+Imin-3*Im/2).*(3*T/4<=x & x<=T);
        I(i,j)=s1(j/n+i/m);
    end
end
imshow(I,[]);

[ajeet verma]

all right but here something is wrong i am not getting image corresponding to graph as shown in attached file.

[KSSV]

YOur code is very slow.....it needs lot of modifications......

[ajeet verma]

if we reduce the value of image size (1000,1000) to (100,100) it works properly,

[ajeet verma]

but desired result is not coming