Joao,

Steve's Workbench, from Radio Shack, has an article discussing the use of a
thermistor with a Basic Stamp II.  The article has a clear explanation of
linearization and even has a simple Gauss fit program in basic.  You can
find the article at
http://www.radioshack.com/sw/swb/projects/stamp/therm.htm

Hope it helps,

Larry
snip
>I am using a sensor of pressure and an operational one that supplies me
>the following values:
>
>
>PSI      Volts
>
>0          1,183
>5          1,440
>10        1,773
>15        2,092
>20        2,471
>25        2,823
>30        3,150
>35        3,460
>40        3,750
>
>When using a test routine multiplying the value of ADRES (PIC16C74A) for
>16 and the routine bin_bcd I get to obtain a reading in display of 40,80
>when in full scale (255).
>
>But as there is not linear of the circuit in subject, I don't get to
>maintain a proportional value in the display to input of  PIC.
snip