為了演示If-Else-End結構，考慮精通MATLAB工具箱中函數(shù)mmono，它檢查一個向量的單調性。


                   ? mmono(1:12)     %  strictly increasing input

                   ans =

                        2


                   ? mmono([1:12  12  13:24])     %  non decreasing input

                   ans =

                        1


                   ? mmono([1  3  2  -1])     %  not monotonic in any sense

                   ans =

                        0


                   ? mmono([12:-1:0  0  -1])     %  non increasing

                   ans =

                       -1


                   ? mmono(12:-1:0)     %  strictly decrasing

                   ans =

                       -2


這個精通MATLAB工具箱的函數(shù)主體給出如下：


          function f=mmono(x)

          %  MMONO Test for monotonic vector.

          %  MMONO(x) where x is a vector return:

          %    2 if x is strictly increasing,

          %    1 if x is non decreasing,

          %   -1 if x is non increasing,

          %   -2 if x is strictly decreasing,

          %    0 otherwise.


          %  Copyright (c) 1996 by Prentice-Hall,Inc.


          x=x(:);        %  make x a column vector

          y=diff(x);      %  find differences between consecutive elements


          if all(y>0)      %  test for strict first 

                     f=2;

          elseif all(y>=0)

                     f=1;

          elseif all(y<0)   %  test for strict first 

                     f=-2;

          elseif all(y<=0)  

                     f=-1;

          else 

                     f=0;   %  otherwise response

          end


    函數(shù)mmono直接利用了If-Else-End結構。由于嚴格單調是一般單調的子集，首先檢驗嚴格的單調是必要的，因為在所碰見的第一個真值分支里，其語句執(zhí)行之后，結構就結束。