How to test for integers and delete integers that do not perform to the test

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Krish Desai
Krish Desai 2015-9-27
编辑： Stephen23 2015-9-27
My assignment: Write a function sumDiv5 which receives one input argument and returns how many elements of the input variable are divisible by 5. You are not allowed to use FOR loops (we will study them next week)
My thinking is to divide the whole input by 5. Then to delete all the non-integer numbers (those not divisible by 5). How do I delete only the non-integer numbers instead of the whole matrix? (which is what my code does)
function output= sumDiv5 (input)
A=input/5;
if isreal(A) && rem(A,1)==0
else
A=[];
end
output=A;

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Image Analyst
Image Analyst 2015-9-27
Close. Study this snippet and see what you can learn:
data = randi(100, 1, 30)
divBy5 = rem(data, 5)
By the way, don't use "input" as a variable name because it's the name of a built-in function.
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Krish Desai
Krish Desai 2015-9-27
编辑：Stephen23 2015-9-27
Ok, I'm displaying the correct for when I have a vector, but when I try to input a matrix:
sumDiv5([0 1 2 3 4; 2 5 8 13 15]),
I get
1 1 0 0 1
Do I have to completely change the code, or is there a simple fix?
Current code:
function output= sumDiv5 (numbers)
A= rem(numbers,5);
count=sum(A==0);
output=count;
Stephen23
Stephen23 2015-9-27
编辑：Stephen23 2015-9-27
Try this:
function out = sumDiv5(mat)
out = sum(0==rem(mat(:),5));
end
And tested:
>> sumDiv5([0 1 2 3 4; 2 5 8 13 15])
ans = 3
Note that I also formatted the code in your question properly: in future please do this yourself by selecting the code text and clicking the {} Code button that you will find above the textbox.

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更多回答（1 个）

James Tursa
James Tursa 2015-9-27
Hint: Take a look at the result of rem(A,1)==0. What do you get if you sum this up?

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