just thinking out loud but do you actually need such a huge range? i am using thermistors in one of my projects and to make my life easier i have narrowed down the range, for example you said that it's for a temp over heat in a circuit! and i notice you live in india, now i have never been there and know very little about india but will your circuit ever be exposed to temps anywhere near -40?
all i am thinking is if you can narrow the band down you have the option of a look up table. also better resolution, or maybe you just need whole degrees and can do without for example 25.6C if thats the case it would make your maths a bit easier.
that tool uncle eric pointed to is the business! saved me loads of time and effort!