topic GEODIST Function - Manual calculation in SAS Programming

GEODIST Function - Manual calculation

InnovativeMinds — Sat, 21 Oct 2017 00:07:53 GMT

Hi All,

Could you please help if there a SAS code to exactly replicate the GEODIST function?
I want to calculate the distance using latitudes and longitudes but it should exactly replicate the outcome of GEODIST function for the same input of latitudes and longitudes.

For ex:
If Distance = geodist(32.5153, -92.1567, 32.53238, -92.07976, 'DM'); is giving 4.6443116482
I want to calculate it manually to get the same value 4.6443116482.

Thanks a lot.

GEODIST function calculation

InnovativeMinds — Fri, 20 Oct 2017 21:43:53 GMT

Hi All,

Could you please help if there a SAS code to exactly replicate the GEODIST function?

I want to calculate the distance using latitudes and longitudes but it should exactly replicate the outcome of GEODIST function for the same input of latitudes and longitudes.

Thanks a lot.

Re: GEODIST function calculation

Reeza — Fri, 20 Oct 2017 21:53:01 GMT

Do you mean manual code? ie

( x**2 + y **2 ) ^ 1/2 .....

Because SAS has a GEODIST function so I'm confused....

Re: GEODIST function calculation

InnovativeMinds — Fri, 20 Oct 2017 21:56:29 GMT

Hi, Yes, I'm looking for manual code not the function.

Re: GEODIST function calculation

InnovativeMinds — Fri, 20 Oct 2017 22:00:11 GMT

For ex:

If Distance = geodist(32.5153, -92.1567, 32.53238, -92.07976, 'DM'); is giving 4.6443116482

I want to calculate it manually to get the same value 4.6443116482.

Re: GEODIST function calculation

Reeza — Fri, 20 Oct 2017 22:06:40 GMT

Out of curiousity, why?

Re: GEODIST function calculation

InnovativeMinds — Fri, 20 Oct 2017 22:11:48 GMT

I need to work and explain non-SAS user how I'm coming up with that (GEODIST) value.

Re: GEODIST function calculation

Reeza — Sat, 21 Oct 2017 00:13:11 GMT

Note that I've merged this into one thread since it's the exact same question.

Re: GEODIST Function - Manual calculation

PGStats — Sat, 21 Oct 2017 04:17:47 GMT

This might be more difficult than you expect. SAS doesn't use the simple great circle distance formulas that you can find on Wikipedia. They are calculating the distance on some ellipsoid approximating the shape of the Earth. You can look at the reference that they give here.

https://www.ngs.noaa.gov/PUBS_LIB/inverse.pdf

Re: GEODIST Function - Manual calculation

Reeza — Sat, 21 Oct 2017 04:27:50 GMT

Before GEODIST() there was a %geodist macro. You can find it via Google, it's relatively close but not exact to the numbers from GEODIST().

Re: GEODIST Function - Manual calculation

InnovativeMinds — Sat, 21 Oct 2017 11:40:11 GMT

Thanks, PG. Appreciate the information.