|Re: HP41CV basic statistics question|
Message #2 Posted by Vieira, Luiz C. (Brazil) on 6 Aug 2003, 6:46 p.m.,
in response to message #1 by Andrew
Hi, Andrew; and welcome!
In the text below, please consider (SIGMA) as a reference to the greek symbol used to represent summation, O.K.? To use the Statistics resources available in the HP41, let's first see what does it offer:
Labeled key [(SIGMA)+] and [SHIFT][(SIGMA)-] are the "starting point" to enter data, but you should first take some initial precautions:
enough registers - if you have the means, check for existing registers. You need at least six registers to compute statistics. If you have an HP41CX or an X-functions module, execute SIZE? and verify if it is bigger than 6. If not, simply execute SIZE 006 or anything bigger and that will be fine.
Default value is SIZE 017 because the statistics resources use a "block" of six consecutive registers starting at R11, i.e., R11 to R16. This block may be changed to any existing position by using [(SIGMA)REG], provided a block of six registers is reserved. In the worst case, use [(SIGMA)REG] 000 to use the first six registers (R0 to R5) and the maximum value is [(SIGMA)REG] 314, when all memory is dedicated to registers and you'll use the block from R314 to R319. In any case, these registers will contain:
R(x) - summation of X
R(x+1) - summation of X^2
R(x+2) - summation of Y
R(x+3) - summation of Y^2
R(x+4) - summation of X*Y
R(x+5) - n (# of sampled data)
where x is the number of the first statistic register, the same one used with [(SIGMA)REG] to define them. Prior to enter data and after defining/knowing the statistics block, execute CL(SIGMA) to clear only the six registers defined for statistics.
To enter data for a double statistic sample:
enter the first value for Y;
enter the related value for X;
repeat these four steps for each remaining pair of sampled data
If it is a sample with one value only, first enter a single 0 [ENTER] and then:
enter the first X value;
repeat these two steps for each remaining X-value
If you enter a wrong data, repeat the input procedure with the wrong data and press [SHIFT][(SIGMA)-] to remove; then you enter the correct data and press [(SIGMA)+] to enter it.
After the data is completely entered, there are two statistical functions that will help you:
[MEAN] - Mean of each value; you'll see the mean value for X and you may press [X<>Y] to see the mean value for Y, if applicable;
[SDEV] - Standard Deviation; works the same as MEAN
Also, you can recall any of the six statistic accumulated data with [RCL] x to [RCL] (x+5) and use it as you need. You can create programs to compute other values.
Hope this helps as a starting point. If you need more advice, let us know.
Edited: 6 Aug 2003, 6:50 p.m.