## Spatial analist - Intersection of two grids

### Spatial analist - Intersection of two grids

Hello

I need to intersect or subtract two grids (spatial analist) that overlap at
some points. I want to get a result grid that as the values of the "overlay"
grid, regardless of the other values. Is there a script or extension to do
this?

Thomas

### Spatial analist - Intersection of two grids

Hello

I need to intersect or subtract two grids (spatial analist) that overlap at
some points. I want to get a result grid that as the values of the "overlay"
grid, regardless of the other values. Is there a script or extension to do
this?

Thomas

Well, it's not quite our task here to help with homework ... :-) That
said, I assume that you are aware of the strange behaviour of exp(1/x)
near x=0 (that can be understood better if one looks at the complex exp
function exp(1/z)). First thing you should do is to make a plot in order
to locate the intersection. Running the command

Maple> plot({exp(1/x), 4*sin(x)/x}, x=-10..10, view=[-10..10,-5..5],
discont=true)

on Maple V, rel. 5, I first had strange problems ("Plotting error,
non-numeric vertex definition"). Splitting the x-range into [-10..0] and
[0..10] had the effect that the first one (neg. arguments) could be
plotted, but not the second one; you have to stay away sufficiently far
from x=0 (x=0.002 works, but not x=0.001). Look at the plots, think
about the long-time behaviour (for x -> - infinity and x -> + infinity)
of both functions, then you know where to locate the intersection: the
two points you see are the only ones. Instead of the command
"fsolve({exp(1/x), 4*sin(x)/x}, {x,y})", you should perhaps rather use
"fsolve(exp(1/x) - 4*sin(x)/x, x,)": that gives you the positive x-value
for intersection. To find the negative one, specify the x-range.

Hope that helps

Gottfried Barthel

Cross-posting to the Maple-specific group comp.soft-sys.math.maple