Wikipedia:Reference desk/Archives/Computing/2018 February 28

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February 28

TCP/IP Interface in biometric Attendance Control System

In Biolite Net attendance control system wires come out of the terminal device are these wires directly connected to a network switch or because Biolite net also has RS485 the wires coming out of Biolite net terminal go to RS 485 to ethernet converter or modem and from that device lan cable like RJ45 goes to the network switch. without the protocol converter means Biolite Net terminal chip DSP 533Mhz has network interface card capability or other auxiliary chip or card with NIC functionality.Will someone please elucidate Wrogh456 (talk) 16:05, 28 February 2018 (UTC)

See http://cdn2.webninjashops.com/netdigital/product-download/blr-oc%20v2_2.pdf which indicates wires 8 9 10 and 11, yellow blue orange and pink are Ethernet connections. There is an adapter cable available to plug these wires to an RJ45. RS485 is something separate on wires 16 to 19. The software setup seen at http://resource.boschsecurity.com/documents/BioLite_Net_Installation_Manual_enUS_24074027659.pdf lets you configure typical IP parameters and where the server is. There is no WiFi. Graeme Bartlett (talk) 01:50, 1 March 2018 (UTC)

Actually I am confused as because i thought since Biolite net has TCP IP interface then it should have a ethernet RJ45/cat 5/cat6 information outlet or socket or port in the Biolite net terminal device but but ethernet is coming out in form of wires Why This was my real intended question icould not find any ethernet port outlet or socket like i can find in desktop cpus in the Biolitenet terminal.Please elucidate.I have searched not found answer anywhere.Wrogh456 (talk) 04:40, 1 March 2018 (UTC) I am a novice here and seeking your guidance and help in understanding a thing through this wonderful platform Let me explain my question with an example .Attendance control system like Biolite net have terminals and these terminals have TCP /IP interface as per specification and have DSP 533MHz processor/CPU but i could not find any RJ45 socket port or outlet in the Biolitenet terminal raw wires are coming as TCP/IP What kind of TCP/IP is Biolite net using what embedde system operating system do this type of device use where the network interface card and where from the BioliteNet terminal get the TCP/IP functionality and ethernet functionality.Each terminal is given an IP address by the Biostar software.How is this possible.Does the Biolite net CPU DSP 533 MHz has network interface card functionality or inside the terminal another network card or chip for this purpose that is producing ethernet frame or TCP IP packetsAnswer for any similar system also be very helpful for me to clear doubt Is this an internet of thing.Wrogh456 (talk) 05:04, 1 March 2018 (UTC)

The device sounds like it has a NIC, but I do not know if that is in the processor chip, or is in another chip on board. Presumably they don't want to spend money on extra interfaces that may not be used. As a traditional security peripheral, the RS285 may be a more common way to connect. But it can also be completely standalone. Graeme Bartlett (talk) 07:49, 1 March 2018 (UTC)

What does chisq.dist do?

I was fiddling with what I think is the basic Pearson's chi squared test in LibreOffice and I'm not sure if this is a bug, feature, or me not knowing about statistics. I set up a hypothetical set of data:

377	423
400	400

where the top row is "real" data, like how many peas are green vs. yellow, and the bottom row is the expected value for a certain cross with 800 peas and equal ratio. The numbers are picked so that when I calculate the population standard deviation, i.e. 2*23^2/400, I get 2.71, which on a chi square table like this comes out at 0.10. When I evaluate CHISQ.TEST(B2:C2,B3:C3) I get 0.103 as I'd expect. But when I do =CHISQ.DIST(2.71,1,0) I get 0.0625. I tried a few obvious things, like taking the square root first assuming it's looking up chi (the LibreOffice help isn't very helpful, and even the Microsoft Office help follows statistics community standards for most tables, the one I cited excepted, by resolutely refusing to say whether it is looking up chi or chi-squared; it says "X"). So I'm not sure what this is, except it's not what I expect. Any ideas? Wnt (talk) 19:26, 28 February 2018 (UTC)

The chisqdist function implements chi-squared distribution. 64.53.18.245 (talk) 22:41, 28 February 2018 (UTC)

That article says that the chi-squared distribution is used for "Chi-squared test of independence in contingency tables", linking the Pearson test I linked above, and contingency table. I used the sample contingency table for male and female left and right handed, getting 0.18246 for the probability. Using (rows-1)(columns-1) = 1 degree of freedom and looking up the sum I got (1.7774) I come up with 0.12304. This is again lower by a factor of about 1.5, but not exactly the same amount lower. I should note though that the LibreOffice CHISQ.DIST and GAMMA.DIST functions match the Microsoft Office testcases at [1] and [2], so this is looking like a matter of understanding what it is statistically rather than finding a bug. Wnt (talk) 23:16, 28 February 2018 (UTC)

Nonetheless... playing with it a bit more, I tried an example =CHISQ.DIST(0.102,1,0), because on the table exceeding a chi-squared value of 0.102 with 1 degree of freedom has 0.75 probability. But the answer I get from the bolded expression is 1.187 ! The mouseover tooltip says "[CHISQ.DIST], CHISQ,DIST.RT : Returns left-tail probability of the cumulative distribution function or values of the probability density function of the chi-square distribution." The Microsoft help says only it "Returns the chi-squared distribution." But our article on cumulative distribution function says that it is a probability, and shows a graph that doesn't go over 1. I know that Microsoft probably rates as one of the heads or horns of the Beast Itself, but do they really have open-source projects and the rest of the world accepting you can have probabilities over 1 now? What am I missing here? Wnt (talk) 23:50, 28 February 2018 (UTC)