Why Does This Definition of a Piecewise Function Produce a Warning Message?

MATLAB issues a warning when defining the below piecewise function

syms y(x); y(x) = piecewise(x<1, x+1, 1<=x<2, x-1);

But when I write

y(x) = piecewise(x<1, x+1, (1<=x) & (x<2), x-1);

the warning message disappears. Could someone point to an example where those two ways of defining a piecewise function produce different results? It seems here that they give identical results.

Answer 1

[Benjamin Thompson]

This is just a warning about good programming syntax. Good programming style is to never leave order of operations in doubt, and add parenthesis where needed to clarify order of operations. While a <= b <= c is good mathematical notation, it may no be clear to a compiler or interpreter how the expression must be evaluated.

[Kareem Elgindy]

Thanks Benjamin. But could you mention any example where the two operations generate different results?

[Benjamin Thompson]

>> -3 <= -2 < -1

ans =

logical

0

>> (-3 <= -2) & (-2 < -1)

ans =

logical

1

[Kareem Elgindy]

Beautiful example!