Re: [eigen] unpleasant surprise mit math functions |

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On 09/26/2012 06:43:10 PM, rupp@xxxxxxxxxxxxxxxx wrote:

Hi Helmut,
just out of curiosity:

`which unified behavior do you expect for exp(A), sin(A) and cos(A),
``with A being a dense matrix? If you want it to act on each entry
``separately, then the result of exp(A) is probably not what a
``significant number of people may expect. However, using a power
``series expansion for exp, sin and cos is clearly not equivalent to
``sin(t.array())...
`

`There are 2 papers title "19 )(new) dubious ways to compute the matrix
``exponential".
``Therefore, a general package like Eigen shouldn't even try to compute
``the "matrix versions".
`

`Furthermore, I have never applied a transcendental function to a
``general matrix componentwise
``but only to vectors. So, for me, it would best if Eigen would allow
``mathematical functions on vectors only.
``By using Eigen::Map one could interprete a general matrix as one long
``vector in the rare cases where one wants this
`functionality for matrices.
Helmut.