Community RSS Feed https://community.wolfram.com RSS Feed for Wolfram Community showing any discussions in tag Physics sorted by active Have problem to create an nxn matrix https://community.wolfram.com/groups/-/m/t/2930626 I have the following state $L=a \sum_{n,m} \left| 0 n m\right&gt;+b \sum_{n,m} \left| 1 (n+1) (m+1)\right&gt;$ lets suppose n,m = 0,1 also $\left| 0 \right&gt; = (1,0)$ and $\left| 1 \right&gt; = (0,1)$ (column vectors) also $\left| m\right&gt;$ and $\left| m\right&gt;$ are n-dimension Unit column vectors. I wanted to create the nxn matrix based on state L. but the result is wrong. in fact 16 elements should be nonzero and the rest should be zero. this is my code &amp;[Wolfram Notebook] : https://www.wolframcloud.com/obj/21740404-6f1d-48e6-a598-4f9690753174 Reza Hamzeh 2023-06-04T14:21:05Z Propulsion matrix of the body of helical Magnetospirillum magneticum cells https://community.wolfram.com/groups/-/m/t/2920289 ![enter image description here] &amp;[Wolfram Notebook] : https://community.wolfram.com//c/portal/getImageAttachment?filename=cecile2_1100.gif&amp;userId=20103 : https://www.wolframcloud.com/obj/763c2bba-8143-4198-b973-59ff1973ad92 Cecile Fradin 2023-05-16T13:33:49Z Quasicrystalline spin foam with matter: computations https://community.wolfram.com/groups/-/m/t/2929437 &amp;[Wolfram Notebook] : https://www.wolframcloud.com/obj/7d7f571c-16be-4b0a-871c-272fc2d83964 Marcelo Amaral 2023-06-02T00:21:24Z Solving the N-pendulum algebraically https://community.wolfram.com/groups/-/m/t/2928722 Solving the N-pendulum algebraically. &amp;[Wolfram Notebook] : https://www.wolframcloud.com/obj/61a8da15-3502-4d34-a1b8-b3bb505ed0e1 Lucien Grondin 2023-06-01T09:34:20Z