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Closed 11 years ago.
How to calculate standard deviation of a single decimal value, in C#
I do it in SAS code as the following:
std(x y m ) = xSTD YSTD mSDT;
It is simply 0 see the wiki article.
Let X be the number
Calculate EV of [x] which is x
Subtract EV from each element in set which is [0]
Take the average of [0] which is 0
Take the square root of 0 which is 0
Related
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Closed 9 years ago.
How do we find the solution of x
say in
2*x=6
using R?
It must be very trivial but I cant find out the appropriate answer.
You can use the solve() function, which can actually handle multiple equations:
solve(2, 6)
The first argument is the left side of the equation, the second is the right side.
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Closed 9 years ago.
I have a file of integer values that range from 0 to 255. A value of zero means black pixel while a value of 255 means a white pixel. Values in between are "gray-like colors". I am searching for a way to invert that file so that 255 gets transformed into 0 and 0 gets transformed in 255 (per example), thus allowing me to successfully obtain the negative of the image.
Is there a way to achieve this? I am sure the answer is a simply mathematical formula using modulo but I can't get to it.
For additional please refer to:
NetPBM
If range of values is 0 - 255
Inverse is 255 - value
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Closed 10 years ago.
Is there a formula that would get me the length of a matrix's diagonal in units? For example if the matrix is 3x3, the diagonal length would be 3.
The diagonal of an NxN matrix is always N.
The diagonal of a non-square matricies is min(nrows, ncols).
Matricies can have units (e.g. stiffness matrix in finite elements for mechanics has physical units of force/length), but I'm not sure how you mean it.
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Closed 10 years ago.
I have boxscore data from the NFL and some of the data is obviously incorrect. For example for some games the number of sacks is negative, which is impossible. This column is named SackNumOff. How do I change any negative values in this column to zero?
Something like this:
dat$columnname[dat$columnname < 0] = 0
Replaces all negative numbers by 0. The idea is that you can use a subset [] both to extract a subset and assign values to a subset.
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Closed 10 years ago.
There seems to be a limit to number of items that can be included in c() function in R (100 items).
Is there any way to evade this limitation?
Thanks in advance.
There is a limit, but it is a limit of vector length, not a limitation of c:
length(eval(call('c', 1:(2^31-1))))
## [1] 2147483647
length(eval(call('c', 1:(2^31))))
## Error in 1:(2^31) : result would be too long a vector