Where is the problem in this if-else structure?

This is an if-else structure of a larger problem. I have simplified it down to the numerals in work here, but can't figure out where lies the problem.

when I evaluate this simple if structure, the program effortlessly outputs a value of "w=1", (The program enters the structure.)

if (1 > 0)&(3 <= 4)
w = 1;
end

But when I evaluate the same above structure inside an if, else if combination the program won't enter in the "elseif structure" for some reason, and only outputs "m=0", whereas I should also get "w=1". What am I doing wrong?

if (4 <= 4)& (3 <= 4)
m= 0;

elseif (1 > 0)&(3 <= 4)
w = 1;
end

Matlab always evaluates:

(4 <= 4)& (3 <= 4)

equals to logical 1. Why won't it then enter inside the if, else-if structure?

[Stephen Cobeldick]

"Why won't it then enter inside the if, else-if structure?"

Because that is what it is supposed to do.

"What am I doing wrong?"

You didn't read the if documentation.

Answer 1

[per isakson]

"whereas I should also get "w=1"." &nbsp No it should not, because doc says "The statements execute only if previous expressions in the if...end block are false.". In your case a previous expression, (4 <= 4)& (3 <= 4), is true. Only the statements following the first expressions that is true will be executed.

See http://uk.mathworks.com/help/matlab/ref/if.html

Answer 2

[John BG]

because in your

if cond1

     elseif cond2

end

cond1 and cond2 are nested, cond2 only happens if cond1 is false. Because in your example cond1 is 1, true, the if exits. It's the way it works.

Try instead

if cond1 
.. 
end;
if cond2 
.. 
end;

or try a switch

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[Guillaume]

or try a switch

Functionally, there is zero difference between switch and elseif. In particular, in matlab (unlike C), only one case can ever be executed.

[John BG]

I didn't mention the command switch to do what he expected elseif to do but it doesn't.

I am just encouraging to try a different command, that does the same, hoping for the understanding of the basic point that 'else' implies exclusion, not the expected inclusion that Abdul wonders about.

Guillame, next comment please add something we do not know, cool?

[Walter Roberson]

Guillame was mentioning something that the original poster probably did not know.