  used as the internal exchange format for most Autodesk products, especially Architecture, Plant 3D, landscape architecture and similar References External links AutoCAD on the Autodesk Application Marketplace Category:1983 software Category:AutoCAD Category:Autodesk Category:Computer-aided design software Category:Computer-aided design software for Windows Category:Computer-aided design software for Linux Category:3D graphics software Category:Companies based in Little Rock, Arkansas Category:Computer-related introductions in 1983Q: What’s the definition of all columnar vectors in linear algebra? Is there a definition of what all columnar vectors are? This is the context: Consider a linear transformation $A$ from $\mathbb{R}^n$ to $\mathbb{R}^m$ and a vector $v\in\mathbb{R}^n$. $Av$ is columnar if and only if $\exists a\in\mathbb{R}^m$ s.t. $\forall w\in\mathbb{R}^n,Aw=av$. A: A column vector is just a vector with an index on it. $v_i$ is the $i$-th element of $v$. In your problem, the “index” is called $j$ and there is an index $i$ in $v$ which is associated with the index $j$. Thus the $i$-th element of $Av$ is the $i$-th element of the vector $Av$. In other words, you need to find a $j$ so that $\text{some }i \text{ such that }v_i=Av_j$. This is how I like to think about it. Ask HN: How do you get through launch day stress? – knes I’m currently running a web startup which launches in one week. In the last couple of months, I’ve worked hard and I’ve got things pretty well in place. Now I’m trying to get excited about the launch.I know all the problems with launch day and it doesn’t help that we’re a somewhat weird startup. But I know it’s going to be fun, and I need to enjoy it. The question is af5dca3d97