MATLAB Answers

## Using nested loops, write a Matlab program that goes through all elements of a matrix (2D array) and replaces every element that is either a multiple of 5 or 7 with -1.

Asked by Ciara Gornoski

### Ciara Gornoski (view profile)

on 2 Apr 2018
Latest activity Commented on by Walter Roberson

### Walter Roberson (view profile)

on 2 Apr 2018
This is what I have so far...
A=input('enter an array');
num_rows = size(A,1);
num_cols = size(A,2);
for i=1:1:num_rows
for j=1:1:num_cols
if A(i,j)/ 5 or 7 = integer
fprintf('-1')
end
end
end
I'm not sure how to identify the multiples of 5 and 7 and make them replace that with the -1

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## 1 Answer ### Roger Stafford (view profile)

Answer by Roger Stafford

### Roger Stafford (view profile)

on 2 Apr 2018

Your test on a number x from your array can be:
if round(x/5)==x/5 | round(x/7)==x/7
(Doing fprintf('-1') just prints out "-1" and is totally useless for your purposes.)

Ciara Gornoski

### Ciara Gornoski (view profile)

on 2 Apr 2018
I did this and I'm still not getting anything.
A=input('enter an array');
num_rows = size(A,1);
num_cols = size(A,2);
for i=1:1:num_rows
for j=1:1:num_cols
if round(A(i,j)/5)==A(i,j)/5 || round(A(i,j)/7)==A(i,j)/7
end
end
end
I'm just able to input an array but it doesn't give me an output.
Walter Roberson

### Walter Roberson (view profile)

on 2 Apr 2018
if ...
A(i,j) = -1;

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