/usr/share/doc/asymptote-doc/src/penimage.asy is in asymptote-doc 2.37-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 | size(200);
import palette;
int n=256;
real ninv=2pi/n;
pen[][] v=new pen[n][n];
for(int i=0; i < n; ++i)
for(int j=0; j < n; ++j)
v[i][j]=rgb(0.5*(1+sin(i*ninv)),0.5*(1+cos(j*ninv)),0);
image(v,(0,0),(1,1));
|