Eigenvalues and the Trace-Determinant Plane of a Linear Map

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Drag the point on the trace-determinant plane[1], and the corresponding eigenvalues are displayed around the unit circle in the complex plane.
The graphic on the left shows the discriminant parabola and the lines for unit eigenvalues. Where in the trace-determinant plane are the eigenvalues the same? Can you make both eigenvalues have modulus one?
Let
A
be a
22
matrix; then the trace
tr(A)
is the sum of the eigenvalues and the determinant
det(A)
is the product of the eigenvalues. The inverse relation is found by using the quadratic formula on the characteristic polynomial.
The eigenvalues of the matrix
A
determine how the orbit/flow behaves. Can you find the critical point at which a period-doubling bifurcation occurs in the map/flow?

External Links

Trace-Determinant Plane

Permanent Citation

George Shillcock
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​"Eigenvalues and the Trace-Determinant Plane of a Linear Map"​
​http://demonstrations.wolfram.com/EigenvaluesAndTheTraceDeterminantPlaneOfALinearMap/​
​Wolfram Demonstrations Project​
​Published: April 1, 2019