Frequently you will want to specify initial or boundary conditions for an equation with more precision than is possible using simple mouse clicks, or you will need to enter a boundary condition at a different point, or again, you will be faced with the need to specify an initial condition for a three-dimensional plot. All of these situations require you to type the condition in. The Initial Conditions dialog box is provided to satisfy this requirement. You may gain access to it either by selecting the Initial Conditions item from the Numerics menu, or by clicking the button on the toolbar labeled IC. In the dialog box, select the condition you want to change by double-clicking it in the list box. The equation specifying the value of that condition will appear in the text box at the top, where you may type in a new value. You must type it in the form x(t)=const, where x represents some variable that you have defined, t represents some value of the independent variable where the condition is to be set, and const is a constant. Examples of acceptable conditions follow
It would even be acceptable, in the case of a two-point boundary value problem, for both of the above conditions to appear in the same dialog box. Only variables that have been defined may be specified. No derivatives are allowed - if you want to specify a condition on the derivative of a function, you must set it on a variable that has been defined to represent that derivative.