hello

why this pdsolve not be answer

pde := diff(T(x, y, t), x, x)+diff(T(x, y, t), y, y) = (1/0.44e-2)*(diff(T(x, y, t), t));
conds := T(0, y, t) = 1, T(1, y, t) = 1, T(x, 0, t) = 1, T(x, 1, t) = 1, T(x, y, 0) = 0;
`assuming`([pdsolve([pde, conds])], [0 <= x and x <= 1, 0 <= y and y <= 1, t >= 0]);
 

hi 

i want to plot this equations , i want to show that step by step and remind previous . i plot with animte plot but it do not show the previous

restart;
with(plottools);
co := blue;
with(plots);

t := 1;
for i from 20 by -1 to 0 do t := t+1; a[i] := -i*x/t+i; p[i] := plot(a[i], x = 0 .. 20, y = 0 .. 20, color = co, thickness = 3) end do;

plots[animate](plot, [a[k], x = 0 .. 20, y = 0 .. 20], k = [seq(i, i = 1 .. 20)]);

how can i define this  operation of diff in matrix

i want to draw a truss with graph theory 

hi

how can i write a number or word on the column or right the row of matrix as this pic