MATLAB Central Newsreader - Minimum Value

Minimum Value

Raju Gain — Tue, 19 Aug 2008 22:52:01 -0400

Hi,

I have a variable which is an array of all positive
numbers. I am trying to find the minimum value in the
varibale other than zero. Can anyone suggest how I can do
this? I was using the min() function before.

Thanks for your time.

Re: Minimum Value

bogfrog — Wed, 20 Aug 2008 03:38:38 -0400

> Hi,
>
> I have a variable which is an array of all positive
> numbers. I am trying to find the minimum value in the
>
> varibale other than zero. Can anyone suggest how I
> can do
> this? I was using the min() function before.
>
> Thanks for your time.
>

min(my_array(find(my_array > 0)))

Re: Minimum Value

Matt Fig — Wed, 20 Aug 2008 04:08:01 -0400

By, "All positive values" it seems you are including zero.
So your array has values >0? There are several ways to
tackle this, here's one that assumes you want to keep a intact:

a = [0 52 200 13 99 8 2 31 29 10 60 0]; % Data.

tmp = a;
tmp(tmp==0) = NaN; % Get rid of your zeros.
min(tmp) % The value you want.

Re: Minimum Value

Walter Roberson — Wed, 20 Aug 2008 06:58:45 -0400

bogfrog wrote:

>> I have a variable which is an array of all positive
>> numbers. I am trying to find the minimum value in the
>> varibale other than zero.

> min(my_array(find(my_array > 0)))

The find() step is unnecessary

min(my_array(my_array > 0))

--
Q = quotation(rand);
if isempty(Q); error('Quotation server filesystem problems')
else sprintf('%s',Q), end

Re: Minimum Value

Paul — Wed, 20 Aug 2008 07:43:02 -0400

"Raju Gain" <supernova5271@yahoo.com> wrote in message
<g8fiqh$1q0$1@fred.mathworks.com>...
> Hi,
>
> I have a variable which is an array of all positive
> numbers. I am trying to find the minimum value in the
> varibale other than zero. Can anyone suggest how I can do
> this? I was using the min() function before.
>
> Thanks for your time.
>

if x is your array:

minvalue = min(x((x~=0)))

Re: Minimum Value

bogfrog — Wed, 20 Aug 2008 08:05:09 -0400

> The find() step is unnecessary
>
> min(my_array(my_array > 0))

Thanks for that. I thought the 0's in the output of a logical expression would cause an index error. But obviously not!

Re: Minimum Value

David — Wed, 20 Aug 2008 09:58:02 -0400

"Raju Gain" <supernova5271@yahoo.com> wrote in message
<g8fiqh$1q0$1@fred.mathworks.com>...
> Hi,
>
> I have a variable which is an array of all positive
> numbers. I am trying to find the minimum value in the
> varibale other than zero. Can anyone suggest how I can
do
> this? I was using the min() function before.
>
> Thanks for your time.
>

maybe something like:

>> a=[0 1 2 3 4 5]

a =

0 1 2 3 4 5

>> min(a(a>0))

ans =

1

>>

Re: Minimum Value

Titus — Wed, 20 Aug 2008 10:13:23 -0400

"bogfrog" <jmcgraw@rcn.com> schrieb im Newsbeitrag
news:15362310.1219219539684.JavaMail.jakarta@nitrogen.mathforum.org...
>> The find() step is unnecessary
>>
>> min(my_array(my_array > 0))
>
>
> Thanks for that. I thought the 0's in the output of a logical expression
> would cause an index error. But obviously not!

That is the reason why logicals were added (somewhere around MATLAB 6.0),
false/true is something different then 0/1:

>> A = [1 2 3];
>> A([true false true])
ans =
1 3

>> A([1 0 1])
??? Subscript indices must either be real positive integers or logicals.

>> A(A~=2)
ans =
1 3

This is called "logical indexing".

Titus