Matlab＆和<运算符

Question

In this expression

lmin=lminflag & ~kmod & actminsub<nsm*pminu & actminsub>pminu;

is the & operator like a bitwise AND operator? lminflag and kmod are both arrays with either logical 1 or 0 as elements and lmin turns out to be either 1 or 0 as well.

Answer 1

Yes.

1. & is a per-element AND operator.
2. && is a scalar AND operator, with conditional execution of the remainder of the statement.

For example, given:

a = true;
b = false;
aa = [true false];
bb = [true true];
fnA = @()rand>0.5; %An anonymous function returning true half the time

Then:

a &  b;  %returns false
a && b; %returns false (same as above)

However

aa &  bb;  %this an error    
aa && bb; %returns the array [true false]

It's more interesting when the operands are functions, with side effects.

b &  fnA;  %Returns false, and the `rand` function is called (including a small performance hit, and an update to the random state)
b && fnA;  %Returns false, and the `rand` function was not called (since `b` is false, the actual value of `fnA` doesn;t effect the result