RTD Temperature Reading
As a quick check, you can assume that if you scale the reading such that 30°C and 60°C are exact, the maximum error will occur near 45°C. So you can calculate that error and see if it is close enough for your purposes. 

Using the DIN curve \$\alpha=0.00385\$, 30°C is 111.67\$\Omega\$ and 60°C is 123.24\$\Omega\$ so mid-scale is 117.455\$\Omega\$. 

The actual resistance for 45°C is 117.47\$\Omega\$, for a difference of 0.015\$\Omega\$ or about 0.04°C, or roughly doubling the error of a 1/10 DIN sensor.