[MATLAB基础] 在别人的matlab上运行正常的代码，在我这里就是没办法运行

[syy819]

我用的是matlab（R2009b），运行以下代码
k='Y';
while((k== 'y')|(k== 'Y'))
F=input('Please input the temperature in degree F:')
C=(5/9)*(F-32)
k=input('Do you want to continue? If yes input Y/y, If not input N/n','s')
end
提示出错，信息是
??? Error using ==> tf.tf at 121
Invalid syntax for the "tf" command. Type "help tf" for more information.

运行这段代码
function std = Std(x)
if length(x)<2;
disp('standard deviation is meaningless for a single number')
disp('please return this program for a vector')
return
end
av=sum(x)/length(x);
stdPw2=sum((x-av).*(x-av))/(length(x)-1);
std=sqrt(stdPw2);
end
提示信息如下
??? Input argument "x" is undefined.
Error in ==> Std at 2
if length(x)<2;

这两段代码在别人的matlab上运行都是正常的，纠结……