why this message error

Hello,

I do not know what means this message error:

Operands to the logical AND (&&) and OR (||) operators must be convertible to logical scalar values. Use the ANY or ALL

functions to reduce operands to logical scalar values.

Error in EXAMPLE_GA_TOUR1 (line 35)

while cond<500 && gg<100

Can anybody help

Answer 1

[Walter Roberson]

The && operator is the "short circuit and" operator. A && B evaluates A, and if A is non-zero, then it evaluates B -- but if A is zero then it does not evaluate B because it knows the test will fail.

The && operator is restricted to working on scalar values.

Looking at the error message, we can predict that either cond is not a scalar, or else gg is not a scalar. You need to think more about what you want to have happen. Do you want to exit the while loop as soon as even one cond value is >= 500? Or do you want to continue the while loop until all cond values are >= 500 ?

You should be using any() or all() to reflect what you want to happen when the variables are non-scalar. Or possibly you should be reviewing your logic to figure out how cond or gg accidentally became non-scalar.

[huda nawaf]

I need even one cond value is >=500

[Walter Roberson]

while all(cond<500) && gg<100

will stop the loop as soon as even one cond value is >= 500

while any(cond<500) && gg<100

will not stop the loop until all of the cond values are >= 500

[huda nawaf]

But it stopped when one cond met the condition which is 500, what happened was that a message error appeared when making the variable cond have an index:

cond(gg)=max(a)

I do not know if that is related to that message. But the message no longer appears when removing the index gg

[Walter Roberson]

Sorry, that is too vague for us to guess what your code is doing.

[huda nawaf]

I want to clarify that

while cond<500 && gg<50

It is working correctly once one of the two conditions is met, the processing will stop. In other words, while the two condition are not met together, the code continue

Not necessary using all.

In fact the cond variable give me different values each time , I wanted to save the values. So saved it in cond(gg) where gg is variable increase one each time.

while cond(gg)<500 && gg<50

I think the message error that appeared becuase of cond(gg), once remove it it is no longer appear.

I hope that clarify the problem.

Thanks