Maple 9 Learning Guide - Maplesoft

46 • Chapter 3: Finding SolutionsFor verifying solutions, you will find that this method is generally themost convenient.Observe that this application of the eval command has other uses.To extract the value of x from the first solution, use the eval command.> x1 := eval( x, soln[1] );x1 := −1Alternatively, you could extract the first solution for y.> y1 := eval(y, soln[1]);y1 := 2Converting Solution Sets to Other Forms You can use this evaluationto convert solution sets to other forms. For example, you can constructa list from the first solution where x is the first element and y is thesecond. First construct a list with the variables in the same order asyou want the corresponding solutions.> [x,y];[x, y]Evaluate this list at the first solution.> eval([x,y], soln[1]);[−1, 2]The first solution is now a list.Instead, if you prefer that the solution for y comes first, evaluate [y,x]at the solution.> eval([y,x], soln[1]);[2, −1]Since Maple typically returns solutions in the form of sets (in whichthe order of objects is uncertain), remembering this method for extractingsolutions is useful.