Question

explain please

What is the value of X at the end of this MATLAB code? X=2; for X = [X, 2*X]; end 2. X= [2 4 6 8] X= [2 4 4 8 4 8 8 16] X= [2 4 6 8 16] X= [2 4 6 4 8] X= [2 4 4 4 8]

Answer 1

*********************program**************************

octave:1> x=2

x = 2

octave:2> for i=-1:-1:-3

> > x=[x,2*x]

> > end

***********************output****************************

x =

   2   4

x =

   2   4   4   8

x =

    2    4    4    8    4    8    8   16

******************************explaination*************************

initial x value=2

for loop starts from -1 till it reaches to -3 by incrementing -1 step at a time

so, for expression                     x=[x , 2*x]

i value	X value	Expression x=[ x, 2*x]	Output
-1	2	=[2,2*2]	[2,4]
-2	4	=[4,2*4]	[4,8]
-3	8	=[8,2*8]	[8,16]

Finally answer will be:

x =

    2    4    4    8    4    8    8   16

Answer 2

The value of X is:

X=

2    4    4    8    4    8    8   16

Correct Answer is:- B

----------------------

Explanation :-

Execute this Code on matlab compiler:-

X=2;
for i=-1:-1:-3
{
X=[X, 2*X];
fprintf('value of x: %d\n', X);
}
end
X

-----------------------------------------------------------------

Initially X=2, now it for loop execute three times(i=-1,-2,-3)

Steps (1). for i=-1, X= 2 and X=[X, 2*X] so X= 2 4

Step (2) for i=-2 , X=4 and X=[X, 2*X] so X= 4, 8

Step (3) for i=-3 and X=[X,2*X] will be 4    8    8   16 (here X=[4, 4*2] will be 4 8 and X=[8, 8*2] will be 8 16)

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Thanks a lot.