[EMAIL PROTECTED] wrote:

> Is this correct?...how MySQL calculate this?...


Yes.

   Std. Dev = Math.sqrt(sum((val[i]-avg)**2) / count(i));

Verified with a trivial program.


> 
> mysql> select * from temp;
> +------------------+
> | cal              |
> +------------------+
> | 0000000000029.98 |
> | 0000000000029.95 |
> | 0000000000029.89 |
> | 0000000000029.84 |
> | 0000000000029.78 |
> | 0000000000029.81 |
> | 0000000000029.84 |
> | 0000000000029.28 |
> +------------------+
> 8 rows in set (0.00 sec)
> 
> mysql>
> 
> mysql> select std(cal) from temp;
> +----------+
> | std(cal) |
> +----------+
> | 0.205240 |
> +----------+
> 1 row in set (0.06 sec)
> 
> mysql>
> 
> 
> 
> 
> R.B.Roa 
> Traffic Management Engineer
> PhilCom Corporation
> Tel.No. (088) 858-1028
> Mobile No. (0919) 30856267
> 
> 
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  • STD() RBRoa
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