# Tagged Questions

87 views

### Select positive value from a vector

I am wondering how to pick out the positive Omega value from soln, and make these positive values into a row vector. I know how ...
2k views

### How to combine two vectors into a matrix by columns?

I know it may sounds idiot, but I've been looking through the document, and couldn't find a way to combine two vectors say {a, b} and ...
100 views

### replace is not happening for specific vector valued expression

Given x[t_] := {Subscript[x, 1][t], Subscript[x, 2][t]} following replace works fine x[t] /. x[t] -> 0 0 but following ...
814 views

### Make a huge vector in a wise way

I need to construct a vector similar to: v[x_]:={0, 0, x, 0, 0, 2*x, 0, 0, 3*x, ....., 0, 0, n*x}; where n=10^9. How can I ...
126 views

### Splitting list of sums into a sum of lists

I want to split a list of sums into a sum of lists For example, I'd like to turn {{x + y + z}, {x}, {y}, {z}} into ...
303 views

### How to pull scalars out of a function that should act on lists?

Suppose I have A = a vecA B = b vecB where a and b are supposed to be arbitrary scalars ...