Technical surprises using VECTORs
>>> UPDATED

Building my tech. example provided me with a bunch of findings htt I want to share.
The first vectors I touched appeared with text analysis and more than 200  dimensions.
I have to confess that I feel well with Einstein's 4 dimensional world.
7 to 15 dimensions populating the String Theory are somewhat across the border.
But 200 and more is definitely far beyond my mathematical horizon.

So I looked to our Globe and found a vector of (latitude,longitude) with 2 dimension is enough for testing.
A handy table of capitals was found and provided sample test data (shortened).

#1
 Loading that TAB separated text file with LOAD DATA (SQL) worked perfect

#2
Transforming the geo coordinates int INT was a minor coding exercises
It resulted in a ClassMethod projected as SQL Procedure used inana UPDATE over the table.

#3
As geo coordinates refer to (0°N,0°W) somewhere in the Atlantic this is just a theoretical base for my vectors.
IRIS supports some VECTOR functions but I found no AddVector() or SubtractVector() function.
so this was done "manually" from the input coordinates.
The need arises from transforming coordinates to a useful base point for later comparing vectors
So you see static BASE coordinates and active WORK coordinates.

Getting the Vector's values is easy with SQL using %EXTERNAL() function
while in ObjectScript I ended up with
        set vectorvalues=##class(%Vector).LogicalToOdbc(vectorvariable) 
this was less impressive for working with Vectors.

#4
Similarity is calculated with VECTOR_COSINE() function.
You calculate the angle between 2 Vectors and COSINE norm it between +1 and -1
The input needs 2 Vectors of the same type and same dimension.
Examples as in documentation work fine if you compose your SQL String as suggested
and TO_VETOR(?,type,size) is OK  with  %SQLStatement  for execution.
BUT:
I tried it with embedded SQL.
Code checking signalled some disagreement but compiled without problem
At runtime it turned out that host variables in TO_VECTOR(:myvec,INT,2) failed
whatever combination of quotes, braces, .... I tried.
So be warned. I returned to  %SQLStatement to get my VCOS done.

UPDATE:  TO_VECTOR(:myvec,INT,2)
     set myvec="1314,-7979" 

Nothing special: Just a plain String with comma-separated values
It seems I couldn't believe that simple approach.
My apologizes to ISC Engineering.

#5
It was a surprise to learn how wide VECTOR_COSINE is spreading.
checking the vector Paris >> Bucuresti  traced half of Middle and East Asia.
So limiting the results to > 0.999 is a good practice in this scenario.

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