Hi all. Today i bumped into this problem:
h = 0.25;
El = 43*10^3;
Et = 8.9*10^3;
Glt = 4.5*10^3;
vlt = 0.27;
n = 4;
vtl =vlt*Et/El;
Dloc = 1/(1 - vlt*vtl)*{{El, El*vtl, 0}, {El*vtl, Et,0}, {0, 0, (1 -vlt*vtl)*Glt}};
c1 = Cos[Pi/4];
s1 = Sin[Pi/4];
T1 = {{c1^2, s1^2, c1*s1}, {s1^2, c1^2, -c1*s1}, {-2*c1*s1, 2*c1*s1, c1^2 - s1^2}};
c2 = Cos[-Pi/4];
s2 = Sin[-Pi/4];
T2 = {{c2^2, s2^2, c2*s2}, {s2^2, c2^2, -c2*s2}, {-2*c2*s2, 2*c2*s2, c2^2 - s2^2}};
D1 = Transpose[T1].Dloc.T1;
D2 = Transpose[T2].Dloc.T2;
Dm = 1/n*(2*D1 + 2*D2)
beta= -(n*h)^2/(2*n)
Dmf = {{0, 0, beta*D2[[1, 3]]}, {0, 0, beta*D2[[2, 3]]}, {beta*D2[[1, 3]], beta*D2[[2, 3]], 0}}
A1 = Inverse[Dm]
B1 = -A1*Dmf
The fact is that Mathematica returns me a B1 matrix full of "0." when it actually shouldn't.
How is it possible that some of the elements of A1 (numbers of the order of 0.0000x) multiplied by some of the elements of Dmf (of the order of 10xx) return 0?
I tried with //N //MatrixForm everywhere and with zero results.
Looking forward to your help. Thanks.
