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Thread: Math problem I'm too stupid to solve

  1. #16
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    Oh God, now that it works, the system tells me i weigh 72.706645304036kg

    I've put on weight!
    "And, look, the luscious and fecund fronds of the Silver Fern has given brilliant birth to a stupendous fruit! A red Hondaberry, desposited by a lesser known species of Plonker Gittus Maximus Idiotus."

  2. #17
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    Quote Originally Posted by mowgli View Post
    The question is still retarded. You better make sure you capture any assumptions you make in answering the question. Like are these integer ranges or real? And what is the relationship between the ranges? Is it linear, logarithmic or something else? There are many ways that values in one range could be mapped to values in the other? It'd be inefficient but you could even do it randomly with a lookup table.

    Who's asking the question?

    Edit: Oh I see now. Back in my box
    I'm the retarded question writer.

    Measuring the milli volt output of a loadcell. machine reads inputs in range of +/-150mV, outputs it over ethernet as a big endian 2 word somethingarather. (in the range of 0-65535).

    Once i scale in a linear fashion from 0-65535, I have the mV reading, which I can then divide by 2mV per V of excitation voltage(15v) at 100kg.

    Err..
    I think.
    "And, look, the luscious and fecund fronds of the Silver Fern has given brilliant birth to a stupendous fruit! A red Hondaberry, desposited by a lesser known species of Plonker Gittus Maximus Idiotus."

  3. #18
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    Remember Joachim's razor boys...
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  4. #19
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    Quote Originally Posted by slofox View Post
    Remember Joachim's razor boys...

    especially given the famed laziness of lecturers. KISS FTW.
    And I to my motorcycle parked like the soul of the junkyard. Restored, a bicycle fleshed with power, and tore off. Up Highway 106 continually drunk on the wind in my mouth. Wringing the handlebar for speed, wild to be wreckage forever.

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  5. #20
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    Quote Originally Posted by Winter View Post
    yes I believe the answer to be 11.707
    It would be 11.705 if your range had 300 integer values in it, but it doesn't. It has 301. -150 to 150 includes zero.

    So you need to divide 301 by 65536, not 300, and the answer is 12.24.

    Unsurprisingly, 'off by one' errors happen a lot in computer programs.

    Did you actually read my initial post?
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  6. #21
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    Quote Originally Posted by jrandom View Post
    First range would make more sense if it was 0 to 65535 (FFFF hex), ie, 65536 distinct values. I'd assume that that's just an error in the form of the question.

    Assuming you have no other information than that brain-dead question form, presumably written by someone who was too stupid to get a real job and has therefore ended up teaching, I'd expect that you're supposed to be using an unsigned 16-bit number to represent a range of -150 to 150 decimal.

    Which means that you divide 301 decimal (the number of values in your represented range) by 65536 decimal (the number of values in your 16-bit integer) and then multiply the result by 35325 and add the result to your minimum value.

    In other words, 12.24.

    But, really, I wouldn't have a clue what I'm on about here. Pay no attention to anything I write.

    (Edited 302 to 301. See, I told you I had no clue. And edited the result to be added to -150, etc. This whole thread is stupid.)




    Quote Originally Posted by Firefight View Post
    forget that, just write an essay on what you did in the weekend

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  7. #22
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    Quote Originally Posted by jrandom View Post
    It would be 11.705 if your range had 300 integer values in it, but it doesn't. It has 301. -150 to 150 includes zero.

    So you need to divide 301 by 65536, not 300, and the answer is 12.24.

    Unsurprisingly, 'off by one' errors happen a lot in computer programs.
    I said i believed it to be 11.707 as thats what the manufacturers software measured it as - I'd be surprised if they got the maths wrong somehow, its an industrial automation product, used to run factory's and so on.
    Quote Originally Posted by jrandom View Post
    Did you actually read my initial post?
    No, Why? Did it say something useful?

    p/t. yes i read it. It said : "That question doesn't make any sense."
    "And, look, the luscious and fecund fronds of the Silver Fern has given brilliant birth to a stupendous fruit! A red Hondaberry, desposited by a lesser known species of Plonker Gittus Maximus Idiotus."

  8. #23
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    Quote Originally Posted by Winter View Post
    I said i believed it to be 11.707 as thats what the manufacturers software measured it as
    Don't ever assume that the manufacturer's software was written by someone smarter than you. In my experience, it usually isn't.

    If the specs really are as you describe, then the manufacturer's software has that exact off-by-one error in its logic and is giving incorrect output.

    Always check actual physical measurements with separate calibrated equipment.

    Quote Originally Posted by Winter View Post
    p/t. yes i read it. It said : "That question doesn't make any sense."
    Come to think of it, I should've just left my contribution to the thread at that.
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  9. #24
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    Quote Originally Posted by jrandom View Post
    Don't ever assume that the manufacturer's software was written by someone smarter than you. In my experience, it usually isn't.

    If the specs really are as you describe, then the manufacturer's software has that exact off-by-one error in its logic and is giving incorrect output.

    Always check actual physical measurements with separate calibrated equipment.
    Looks like your right there - my software is giving slightly higher results than theirs.


    Thanks for your input.
    "And, look, the luscious and fecund fronds of the Silver Fern has given brilliant birth to a stupendous fruit! A red Hondaberry, desposited by a lesser known species of Plonker Gittus Maximus Idiotus."

  10. #25
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    Quote Originally Posted by Winter View Post
    Mind block or something, help me out here.


    range one = 0 to 65,536
    range two = -150 to +150
    value in range one (35325) = what value in range two?


    Steps needed to work this out? they told me I needed pay attention in maths if I wanted to work in computers... I didn't believe them :S
    What you need is a Range Rover.

  11. #26
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    Where's Hitcher?

    It's "maths" not "math". We are not in 'merica.

    As for the question, I'm a simple freight forwarder, so I dunno.
    Quote Originally Posted by rachprice View Post
    Jrandom, You are such a woman hating cunt, if you weren't such a misogynist bastard you might have a better luck with women!

  12. #27
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    After 10 pages could someone please be courteous enough to summarise the problem and answer to it

  13. #28
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    How linear is the output of the strain gauge of the weigh cell.
    Also depends on the accuracy of the analogue input card, and whether the A to D converter has span and zero correction or a fixed constant as a correction.

  14. #29
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    Quote Originally Posted by mynameis View Post
    could someone please be courteous enough to summarise the problem
    So far we seem to have established that most electronic and software engineers are stupid, and basic arithmetic is the only 'math' you need to know to write computer programs.
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  15. #30
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    Quote Originally Posted by Mully View Post
    As for the question, I'm a simple freight forwarder, so I dunno.
    Try being a bum on a bicycle. This shit does my head in.
    kiwibiker is full of love, an disrespect.
    - mikey

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