H Peyrovedin - Fars- Shiraz
P Keshavarz - Shiraz University-Mollasadra street -Fars- Shiraz

In this study collocation method and orthogonal collocation method have been used to determine the temperature distribution and efficiency of various types of fins with temperature-dependent thermal conductivity. These methods are very easy and straight forward for solution of nonlinear ordinary differential equations. By using these methods the functionality of temperature vs. the length of fin and fin efficiency have been calculated in the form of mathematical formula and finally The results are Compared with previous works and exact solution