【求助】yesinput函数问题

源程序中有N=yesinput('Input The length of the windows N=:\n',15,[10,64]);编译后
??? Undefined command/function 'yesinput'.

Error in ==> FIR at 1
N=yesinput('Input The length of the windows N=:\n',15,[10,64]);
为什么会这样？