How I can plot a graphic with three parts

clc;clear

CC = input ('Ingrese la COMPLIANCIA (cm3/cmH2O)DEL PULMON C = ');

C= CC/981;

subplot (2,2,1)

syms t

% I need to fplot a graphic that 0<t<3, and 0<t<=1 is '1', then 1<t<=2 is t;

% and 2<t<=3 is '2'. After that this graphic named Q, fplot and insert in

% this line... Please help me

hold on

grid on

fplot(Q,[0 3])

title ("FLUJO/CAUDAL Q, VARIANTE RESPECTO AL TIEMPO")

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Ro=1; G=981; A1=100; A2=150; A3=125;

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syms x

Vol =(Q*t)

subplot (2,2,3)

hold on

grid on

fplot(Vol,[0 3])

title ("VOLUMEN, VARIANTE RESPECTO AL TIEMPO")

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RO=1; G=981;

h=Vol/(C*RO*G)

subplot (2,2,4)

hold on

grid on

fplot(h,[0 3])

title ("PRESION, VARIANTE RESPECTO AL TIEMPO")