[求助]请叫关于离差的概念

[cfx]

在matlab中多项式拟合[y delta]=polyval()中delta表示拟合的离差不知该如何理解，请高人解答！谢谢！

[glinfeng05]

[Y,DELTA] = POLYVAL(P,X,S) or [Y,DELTA] = POLYVAL(P,X,S,MU) uses
the optional output structure S provided by POLYFIT to generate
error estimates, Y +/- delta. If the errors in the data input to
POLYFIT are independent normal with constant variance, Y +/- DELTA
contains at least 50% of the predictions.