topic Re: std deviation and square root in Application Development and Automation Discussions

std deviation and square root

Vijay — Mon, 10 Mar 2008 08:27:21 GMT

hi all

i have a requirement where i need to calculate the standard deviation and squre root of some variables.

can anybody please tell how can i calculate that in abap.

regards

vijay

Re: std deviation and square root

Former Member — Mon, 10 Mar 2008 08:32:02 GMT

You can use the function module

1. 'QRKT_STD_DEVIATION_SHEWHART'-Algorithms for Shewhart chart for s with internal dispersion and mean line

2.'QRKT_STD_DEVIATION_SHEWHART_2'- Algorithms for Shewhart chart for s with overall dispersion and mean line.

You could also calculate it yourself of course - standard deviation is the square root of the sum of the square of the differences between the mean and each value divided by the number of values you have less one.

Reward points..

Re: std deviation and square root

Former Member — Mon, 10 Mar 2008 08:38:53 GMT

Hi,

try this code..


data : begin of it occurs 1,
num type p,
x_xbar type p, 
end of it.

data : num1 type p value 10.
data : tot type p,l(2),
total type p. " E(x - mean)^2
data : mean type p.
data : var type p,
sd type p.

do 5 times .
it-num = num1.
append it.
num1 = num1 + 10.
enddo.

loop at it .
tot = tot + it-num.
endloop.

describe table it lines l.

mean = tot / l.

loop at it .
it-x_xbar = ( it-num - mean ) * ( it-num - mean ).
total = total + it-x_xbar.
endloop.

var = ( total ) / ( l - 1 ).
sd = SQRT( var ).

write : sd.

for square root


DATA : in TYPE f VALUE 16 ,
out TYPE f .

CALL METHOD cl_foev_builtins=>square_root
EXPORTING
im_number = in
IMPORTING
ex_result = out.

WRITE out.

Regards,

Omkar.

Re: std deviation and square root

Former Member — Mon, 10 Mar 2008 08:44:32 GMT

Hi,

You can use the SQRT to compute the square root.

Check the code.

data: var(3) type n,

sqt(3) type n.

var = 100.

sqt = sqrt( var ).

write: / sqt.

For Std deviation, you need to compute it manually or by using the function module

'QRKT_STD_DEVIATION_SHEWHART'

Reward if helpful.

Regards.