Stuart Bivens & Tristan Ursell
[xterp yterp] = streamfun(x,y,u,v,xq,yq)
[xterp yterp] = streamfun(x,y,u,v,xq,yq,dt)
Given a vector field specified at the positions by x and y, with the vector field values specified by u and v, this function will interpolate the vector field at the specified points xq and yq and then compute their linear movements with a step size dt.
x and y are meshgrid positions of the vector field
u and v are values of the vector field
xq and yq are the positions of the sample points to be advanced
dt is an optional multiplier used to adjust length of interpolated vectors, defaults to 1.