This page summarizes common errors.
Matlab permits you to redefine anything, which can lead to unexpectedly masking basic functionality. For example:
» sum(0:25)
ans =
325
» sum = 0
sum =
0
» sum(0:25)
??? Index into matrix is negative or zero.
»
The problem is that when you say "sum = 0" you have redefined "sum"!
If you type the line "sum(0:25)" only long after you have
redefined sum, you might be very confused. How could this basic
Matlab function not work? Typing "help sum" will only make
this confusion worse, since every careful reading of the information
it gives you indicates that sum(0:25) will work.
The fix is:
» clear sum
» sum(0:25)
ans =
325
»