Determine how many times numbers in a certain range were drawn
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Hi All I have a 52,1 matrix populated with random matrix.
I want to be able to count the sum of a range, for example I want to be able to sum the values between the (3,1) and (6,1)
I tried using the code range=sum(matrixname(lowvalue:highvalue))
but that does not work
Any suggestions are appreciated
Thanks!
Rich
3 Comments
Evan
on 23 Jul 2013
When you say "that does not work" what do you mean? Do you get an error? Is this value returned simply wrong?
Image Analyst
on 24 Jul 2013
And what does it mean to count the sum? The sum is the total of the numbers. What is the "count" of that?
Answers (1)
dpb
on 23 Jul 2013
On the assumption the (3,1) refers to the subscript of the array (and, btw, the "1" is superfluous for the 1D dimension for vectors, use just "(3)" instead),
>> x=rand(52,1);
>> x(2:7)'
ans =
0.7138 0.8844 0.7209 0.0186 0.6748 0.4385
>> sum(x(3:6))
ans =
2.2986
>> nlow=3;nhi=6;
>> sum(x(nlow:nhi))
ans =
2.2986
>>
If, instead you mean the between the values stored at those locations, then use logical addressing...since don't know the magnitudes of the values at those locations, to do logic on them will need to find the larger/smaller first...
>> xlo=min(x(nlow),x(nhi))
xlo =
0.6748
>> xhi=max(x(nlow),x(nhi))
xhi =
0.8844
>> (x(x>=xlo & x<=xhi))
ans =
0.7138
0.8844
0.7209
0.6748
0.8147
0.7223
0.8319
0.8593
0.8266
0.8186
>> sum(x(x>=xlo & x<=xhi))
ans =
7.8673
>>
Of course, your answers will be different depending on the values returned by rand()
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