## 133 Reputation

17 years, 70 days

## Eigenvectors of 2x2 Matrix with trig fun...

Maple
How can I evaluate the eigenvectors of a 2x2 Matrix with trig functions as entries? This is what I did: ```with(LinearAlgebra): K:=<<cos(theta)|sin(theta)>,<sin(theta)|-cos(theta)>>; Eigenvectors(K); Error, (in LinearAlgebra:-LA_Main:-Eigenvectors) expecting either Matrices of rationals, rational functions, radical functions, algebraic numbers, or algebraic functions, or Matrices of complex(numeric) values ``` I'm wondering why cos(theta) shouldn't be an algebraic function ?? Assuming theta to be real I get the same.

## How do I assume Maple expression to be a...

Maple
Hello, in a differential equation (in Maple 10) a variable should be replaced by a constant K so that all differentiations of this variable should evaluate to zero. This is my code: ``` constants:= constants, K: myDG1:= u(t) + diff(u(t),t)^2 + v(t)=0: subs(u(t)=K,myDG1); ``` K+(diff(K, t))^2+v(t) = 0 Although I have already assigned K to be constant, Maple doesn't replace d/dt K by 0. Any help would be appreciated.
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