# SECTION 9.1

# Example 1

with(linalg);

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?matrix

A := matrix([[2,t^2,0,4*t+exp(t)],[0,sin(t),cos(t),0],[1,1,1,1],[0,0,0,0]]);

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x := [x1(t),x2(t),x3(t),x4(t)];

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diff(x,t) = multiply(A,x);

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diff(x,t) = evalm(A &* x);

# Example 2

x := [y(t),v(t)];

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A := matrix([[0,1],[-k/m,0]]);

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diff(x,t) = evalm( A &* x);

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# Example 3

x := [x1(t),x2(t),x3(t),x4(t)];

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A := matrix([[0,1,0,0],[-3,0,1,0],[0,0,0,1],[2,0,-2,0]]);

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diff(x,t) = evalm(A&*x);

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