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From:Gerald Clark Date:July 3 2001 12:58pm
Subject:Re: problems with float calculations?
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Thomas J Keller wrote:

> OK.  Radius contains the radius, in miles, from the center of the Zipcode area.
> In the following query, the latitudes and longitudes have been calculated to 
> yield a 20 X 20 mile square centered on the base Zipcode (in this case, 68504).
> 
> +-------+---------+----------+-----------+
> | zip   | city    | latitude | longitude |
> +-------+---------+----------+-----------+
> | 68462 | WAVERLY |  40.9139 |   96.5270 |
> | 68504 | LINCOLN |  40.8391 |   96.6565 |
> +-------+---------+----------+-----------+
> 2 rows in set (0.09 sec)
> 
> DEBUG: query = SELECT * FROM zipcodes WHERE (latitude BETWEEN '40.694382199711'
> AND
> '40.983817800289') AND (longitude BETWEEN '96.547008929014' AND
> '96.765991070986') ORDER BY state, county, city, zip ASC
> 
> 68504:   Radius: 10 Distance 0 miles
> 
>    Waverly (68462) should have been selected in this query, but is not.  As you

No, WAVERLY's longitude is not between 96.547008929014 and 96.765991070986.


> will 
> see by the following query (with radius set to 12 miles) Wavery is less than 9
> miles from 68504.
> 
> 
> DEBUG: query = SELECT * FROM zipcodes WHERE (latitude BETWEEN '40.665438639653'
> AND
> '41.012761360347') AND (longitude BETWEEN '96.525110714817' AND
> '96.787889285183') ORDER BY state, county, city, zip ASC
> 
> 68462:   Radius: 12 Distance 8.5137543957707 miles
> 68504:   Radius: 12 Distance 0 miles
> 
> 
> NOTE:  I have also tried :
> 
> DEBUG: query = SELECT * FROM zipcodes WHERE (latitude > 40.665438639653 AND
> latitude < 41.012761360347) AND (longitude > 96.525110714817 AND longitude
> <
> 96.787889285183) ORDER BY state, county, city, zip ASC
> 
>   With the same results.  
> 
> NOTE:  on advice from somone in #mysql, I tried altering the columns from float
> to
> decimal.  Made no difference at all.
> 
> 
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-- 
Gerald L. Clark
gerald_clark@stripped

Thread
problems with float calculations?Thomas J Keller3 Jul
  • Re: problems with float calculations?Gerald Clark3 Jul