how to generate random isotropic vectors using R?

Matlab: Generating vectors for altitude and density...?

• I'm trying to generate vectors for altitude and density from 0-30 km in increments of 1 km using a FOR LOOP. I have density as 'd' and altitude as 'z' and d=1.42 e ^ -0.141z . I am having a difficult time in developing the program and get errors no matter what I do. This is what I've gotten so far, and I know it isn't right, so if someone could point me in the right direction, I'd appreciate it. for k=0:1:30; altitude(k)=altitude; density(k)=1.42*exp(1)exp(-0.141*altit… end I may be way off base, thus the reason behind me asking for help. Thanks!

• Answer:

  You're on the right track. First of all, notice this error your code: altitude(k)=altitude. You're telling MATLAB that it should set an array element equal to an entire array, which it can't do. You probably meant: altitude(k)=k; Next, notice the error in your equation. You should delete these characters: "exp(1)", so that your equation becomes: density(k) = 1.42 * exp( -0.141*altitude(k) ) If you are required to use for-loops for some reason, then your code should be fine after you fix those problems. However, remember that MATLAB can save you time by performing element-by-element math with EVERY array element. For example, here's some streamlined code, to get the answer without using for-loops: z = [0:30] d = 1.42*exp(-0.141*z)