You mean analogRead(), not analogWrite()
For a large range of temperature the Steinhart–Hart equation will be best simply because it has the rightform and fewer parameters are needed to get a good fit - otherwise a polynomial or rational functionapproximation with more parameters would be needed.
So to use your thermistors, measure resistance (or analog voltage on the Arduino) at 0C, 25C, 50C, 75C and 100C. Plot a curve and apply a little high school math to interpolate between the values.
Look here: it's a good article about thermistors, includes math and a table as I remember...http://www.phanderson.com/picaxe/lin_thermistor.html.
Plot a curve and apply a little high school math to interpolate between the values.