Exponential of the matrix I want to calculate the matrix exponential $e^{tA}$ of the matrix with the first row being $(0,1)$ and the second $ (-1,0)$. It would be sufficient if you would me the most important steps.

Firstly, you should expand an exponent in Taylor series.
Then, you should understand, what happens with matrix, when it is exponentiated with power n.
The last step is to sum up all the matrices and realize, if there are Teylor series of some functions as an entries of the aggregate matrix.  
