%
%  code03.m -- 18 oct 02 -- djm
%
%  #3.9.15 plotting code
%

%  clear workspace & graphics ("help clear", etc)

clear;  close all

%  set vector of t-points for 3 intervals

t1 = 0   :pi/50:  pi;
t2 =   pi:pi/50:2*pi;
t3 = 2*pi:pi/50:6*pi;

%  calculate u-values in each interval

F0 = 1;
u1 = F0*(t1 - sin(t1));
u2 = F0*(2*pi -t2 - 3*sin(t2));
u3 = F0*(-4*sin(t3));

%  calculate derivatives in each interval

up1 = F0*(1 - cos(t1));
up2 = F0*(-1 - 3*cos(t2));
up3 = F0*(-4*cos(t3));

%  plot line graph of u(t)

figure(1);  
subplot(2,1,1);  hold on
plot(t1,u1,'b')
plot(t2,u2,'r')
plot(t3,u3,'b')

%  plot 3 IVs for each interval

plot(0,0,'bx')
plot(pi,F0*pi,'rx') 
plot(2*pi,0,'bx') 

axis([0 6*pi -5*F0 5*F0]);

%  label plot ("\bf"-prefix makes text boldface)

title(['\bf the continuous solution for #3.9.15'])
xlabel('\bf t-axis')
ylabel('\bf u(t)-axis')
text(pi/2,2,'x''s mark IVs for each interval')

%  plot line graph of u'(t)

subplot(2,1,2);  hold on
plot(t1,up1,'b')
plot(t2,up2,'r')
plot(t3,up3,'b')

%  plot 3 IVs for each interval

plot(0,0,'bx')
plot(pi,F0*2,'rx') 
plot(2*pi,-F0*4,'bx') 

axis([0 6*pi -5*F0 5*F0]);

%  label plot ("\bf"-prefix makes text boldface)

title(['\bf the continuous derivative for #3.9.15'])
xlabel('\bf t-axis')
ylabel('\bf u''(t)-axis')
text(pi/2,4,'x''s mark IVs for each interval')