> tr:=x-> if (x>=(-4) and x<(-2)) then (x+4) elif (x>=-2 and x<0) then -x elif (x>=0 and x<2) then x elif (x>=2 and x<4) then -(x-4) fi;

> plot(tr,-3..3);

>

> sq:=proc(x) if (x>=(-2*evalf(Pi)) and x<(-1*evalf(Pi))) then 1 elif (x>=-1*evalf(Pi) and x<0) then -1 elif (x>=0 and x<evalf(Pi)) then 1 elif (x>=evalf(Pi) and x<2*evalf(Pi)) then -1 end if end proc;

>

> plot(sq,-5..5);

>

> f:=(x,n)->1-8/(Pi^2)*sum('cos((2*k-1)*Pi*x/2)/(2*k-1)^2',k=1..n);

> f5:=x->f(x,5);

> plot([tr,f5],-3..3);

> plot(tr-f5,-3..3);

> plot(tr-f2,-3..3);

> g:=(x,n)->(4/Pi)*sum('sin((2*k-1)*x)/(2*k-1)',k=1..n);

> g2:=x->g(x,2);

> g5:=x->g(x,5);

> plot([sq,g2,g5],-5..5);

> plot([sq-g2,sq-g5],-5..5);

> plot(sq-g2,-5..5);

> plot(sq-g5,-5..5);

>