why am i not getting the desired result ?

my code is here

%TWO STEP PHASE SHIFTING TRIANGULAR TECHNIQUE (WAVE FORM)
%%STEP FIRST
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);
s2= @(x) ((-2*Im*x/T)+Imin+Im/2).*(0<=x & x<=T/4) + ((2*Im*x/T)+Imin-Im/2).*(T/4<=x & x<=3*T/4)+((-2*Im*x/T)+Imin+5*Im/2).*(3*T/4<=x & x<=T);
x = linspace(0, 20);
X = repmat(x, 1000, 10);
I1 = s1(x);
I2 = s2(x);
figure(1),plot(x,I1)
figure(2),plot(x,I2)
%%STEP-2 (wrapped map)
r=abs(I1-I2)/Im;
figure(3),plot(x,r)
%%STEP-3 (unwrapped map)
R=4;
up=2*round((R-1)/2)+((-1)^R+1)*r;
figure(4),plot(x,up)

something is wrong in step 3 because i am not getting as i need, so please help please find attachment

[KSSV]

Tell what problem you face? Any error? or what?