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0 Is there a way to rewrite the matrix below using operations like $vec$ , $otimes$ , etc? $left[begin{array}{c} I_notimes e_1\ vdots \ I_n otimes e_T end{array}right]$ $e_i$ is the $i$ -th column of the matrix $I_T$ , $otimes$ is the Kronecker product. I need to rewrite this matrix to make it faster to work with when programming. linear-algebra share | cite | improve this question asked Nov 13 '18 at 15:52 An old man in the sea. 1,622 1 10 32 add a commen

2 I need to write Mathematics, but I would like to avoid Latex for quick notes that I wish to send to colleagues. So I would like to have somewhere to write with some sort of pen, in such a way that 1) what I write appears on the display of my computer (please note that I don't have an iPad, just a Macbook) 2) it gets saved on my computer when I finish. These are just quick notes, so no special drawing features are required (on the contrary, the simpler/cheaper the better). What should I consider? Since I own a Macbook, also writing on the built-in trackpad would be fine, but I've heard that the Inklet app slows down the computer in a very nasty way... Thank you very much in advance. hardware-recommendation handwriting