Moving Minimum/Max?
in [Matlab]
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From: Jacob Haynes on 4 Dec 2009 12:57 Hi, first of all, I have matlab R2009b. I am trying to intemperate data for a college project. (Multilpe 70,000 line peaces) It is from a "satellite" that was launched to 30KM on a weather balloon. The data is from solar panels, one of which overloaded the ADC on the micro-controller we were using because of a huge, unexpected increase in efficiency when at cold temperatures, which wasn't taken into account when choosing resistor values. They were mounted on the sides of a spinning cube, and when out of the sun, they were below the limit of the ADC. Well to get to the point, I need matlab to find a moving minimum, or whatever it is called. Something like a moving average except, I would like to have it find the minimum over 1000 points or so. How can I do this. BTW I am very inexperienced with matlab, and had never used it before doing data analysis with it a few weeks ago.
From: dpb on 4 Dec 2009 13:36 Jacob Haynes wrote: .... > Well to get to the point, I need matlab to find a moving minimum, or > whatever it is called. Something like a moving average except, I > would like to have it find the minimum over 1000 points or so. How > can I do this. BTW I am very inexperienced with matlab, and had never > used it before doing data analysis with it a few weeks ago. How about a very short (10 elements or so) example of input and desired output??? --
From: ImageAnalyst on 4 Dec 2009 13:59 On Dec 4, 12:57 pm, "Jacob Haynes" <ezupeve_...(a)yopmail.com> wrote: > Hi, first of all, I have matlab R2009b. > > I am trying to intemperate data for a college project. (Multilpe 70,000 line peaces) > It is from a "satellite" that was launched to 30KM on a weather balloon. The data is from solar panels, one of which overloaded the ADC on the micro-controller we were using because of a huge, unexpected increase in efficiency when at cold temperatures, which wasn't taken into account when choosing resistor values. They were mounted on the sides of a spinning cube, and when out of the sun, they were below the limit of the ADC. > > Well to get to the point, I need matlab to find a moving minimum, or whatever it is called. Something like a moving average except, I would like to have it find the minimum over 1000 points or so. How can I do this. BTW I am very inexperienced with matlab, and had never used it before doing data analysis with it a few weeks ago. -------------------------------------------------------------------------------------------------------------------- Jacob: If you have the Image Processing Toolbox you can use the imerode() function. A morphological erosion on a grayscale image is a moving minimum - the minimum in a window that slides along your data. If you don't have that toolbox, you should be able to use bsxfun(). Good luck, ImageAnalyst
From: Bruno Luong on 4 Dec 2009 14:08 Please take a look at this function. Mex setup is required, but it will be hard to beat the speed performance http://www.mathworks.com/matlabcentral/fileexchange/24705-minmax-filter Bruno
From: Jos (10584) on 4 Dec 2009 17:15 "Jacob Haynes" <ezupeve_115(a)yopmail.com> wrote in message <hfbihh$2tf$1(a)fred.mathworks.com>... > Hi, first of all, I have matlab R2009b. > > I am trying to intemperate data for a college project. (Multilpe 70,000 line peaces) > It is from a "satellite" that was launched to 30KM on a weather balloon. The data is from solar panels, one of which overloaded the ADC on the micro-controller we were using because of a huge, unexpected increase in efficiency when at cold temperatures, which wasn't taken into account when choosing resistor values. They were mounted on the sides of a spinning cube, and when out of the sun, they were below the limit of the ADC. > > Well to get to the point, I need matlab to find a moving minimum, or whatever it is called. Something like a moving average except, I would like to have it find the minimum over 1000 points or so. How can I do this. BTW I am very inexperienced with matlab, and had never used it before doing data analysis with it a few weeks ago. It is one of those jobs SLIDEFUN can do quite easily % some data data = ceil(10*rand(1,20)) ; n = 3 ; % moving minimum over 3 points movmin = slidefun(@min,n,data,'forward') ; % show results [data ; movmin] My SLIDEFUN function can be found here: http://www.mathworks.com/matlabcentral/fileexchange/12550 hth Jos
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