circle Temperature Model

Alright here's the first small add-on to your code. Should compile successfully. Oh and, I have set it so that by default a circular temperature model is set in the exampleParameter file. 
Quick note, under the (rows, columns) pattern, 'i' would be the index in the y-direction and 'j' would be the index in the x-direction. Because of that, you've got your center_x and center_y backwards. Other than that, it looks good. I'll merge and fix it on my end.