请高手帮忙，指点迷津

matlab编程出现错误提示为：??? Capitalized internal function J; Caps Lock may be on.

                          Error in ==> F:\work\data1\icajik.m
                          On line 5  ==> x1test=reshape(testdata1',1,J*K);

不知道该如何解决，请高手不吝赐教：）