Hi out there,

I have two questions today...

1. Is there a FAQ (frequently asked questions) or FEP (frequently encountered

problems) list for grassp?

2. The following segment of code is from s.surf.idw main() and is used to

calculate the distance between points so that weights for interpolation

can be calculated based on the distance between them...

/* fill list with first nsearch points */

for (i = 0; i < nsearch ; i++)

{

dy = points[i].north - north;

dx = points[i].east - east;

list[i].dist = dy*dy + dx*dx;

list[i].z = points[i].z;

}

/* find the maximum distance */

maxdist = list[max=0].dist;

for (n = 1; n < nsearch; n++)

{

if (maxdist < list[n].dist)

maxdist = list[max=n].dist;

}

/* go thru rest of the points now */

for ( ; i < npoints; i++)

{

dy = points[i].north - north;

dx = points[i].east - east;

dist = dy*dy + dx*dx;

if (dist < maxdist)

{

/* replace the largest dist */

list[max].z = points[i].z;

list[max].dist = dist;

maxdist = list[max=0].dist;

for (n = 1; n < nsearch; n++)

{

if (maxdist < list[n].dist)

maxdist = list[max=n].dist;

}

}

}

My question here: how does this work in the latitude longitude

system, where you really need some spherical geometry to calculate

distance?

thinking i've missed something (as usual) in Oz

chris

--

|\/\/\/| Chris Skelly

| | School of Earth Sciences

| | High expolsives and Macquarie University

| (o)(o) school do NOT mix. North Ryde, 2109, NSW, OZ

C _) Tel: 612-805-8433

| ,___| Fax: 612-805-8428

| / chris@mqclimat.cic.mq.edu.au