An important concern in the study of heat transfer is to determine the steady- state temperature distribution of a thin plate when the temperature around the boundary is known. Assume the plate shown in the figure represents a cross section of a metal beam, with negligible heat flow in the direction perpendicular to the plate. A mesh is showing in the figure. The temperature at a node is approximately equal to the average of the four nearest nodes-to the left, above, to the right, and below. For instance,