Results 1 to 9 of 9

Math Help - how can i derive a function for a real world incident?

  1. #1
    Newbie
    Joined
    Sep 2006
    Posts
    22

    how can i derive a function for a real world incident?

    i wanted to know is the following steps are what i should do to derive a function for a real world incident (to be more specific Digital Signals and moving objects):
    1-i should know all the independant variable that may affect my dependant variable that i want to know about.
    2-study the relation between each independant variable and the dependant variable from the point of view for it's(the independant variable like time for example) sign (can't be negative) .

    don't know what's next to derive a function to describe it's behavior.and when should i use a cos,tan ,cot in a function (for example u raise a term by 2 then take the square root of it to make sure it is not negative or gets the absolute value for this term).
    sorry guys my q might seem silly but i'm not native english so i'm not quite familiar with english terms for mathmatics like real number ,rational ,irrational ,imaginary numbers ..etc
    thanks again and sorry for the long post
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by mHadad
    i wanted to know is the following steps are what i should do to derive a function for a real world incident (to be more specific Digital Signals and moving objects):
    1-i should know all the independant variable that may affect my dependant variable that i want to know about.
    2-study the relation between each independant variable and the dependant variable from the point of view for it's(the independant variable like time for example) sign (can't be negative) .

    don't know what's next to derive a function to describe it's behavior.and when should i use a cos,tan ,cot in a function (for example u raise a term by 2 then take the square root of it to make sure it is not negative or gets the absolute value for this term).
    sorry guys my q might seem silly but i'm not native english so i'm not quite familiar with english terms for mathmatics like real number ,rational ,irrational ,imaginary numbers ..etc
    thanks again and sorry for the long post
    I think this is not specific enough to answer.

    Is this a question about target azimuth, elevation, range, Doppler for
    a radar like system?

    RonL
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Sep 2006
    Posts
    22
    well i can not be more specific as i'm not having a specific problem yet.well i think that i must be more specific regarding my problem as i don't think that the answear will be from one part of mathmatics but i'm sure that it will be mostly a calculus answear.thanks captain jack.
    captain are rational numbers any number that is represented by a two number division which means a decimal number (or as we say it in programming a float) and irrational numbers are the opposite which are integers?
    how can a number that is raised by the power of 2 be negative ,i mean how can i^2 = -1 (can u show me a real world example where i^2 = - 1 so i can understand it more)?
    thanks again captain jack
    Last edited by mHadad; September 2nd 2006 at 11:49 PM. Reason: wrong typing
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by mHadad
    captain are rational numbers any number that is represented by a two number division which means a decimal number (or as we say it in programming a float) and irrational numbers are the opposite which are integers?
    Loosely speaking a rational number is a number that can be expressed as the
    ratio of two integers.

    Again loosely speaking decimal numbers with no restriction on the length of the
    decimal are what we call real numbers.

    Floats are meant to be a computer representation of numbers. But the
    restrictions of computer hardware result in them in fact being a subset
    of the rationals, also floating arithmetic is not the same as normal arithmetic,
    see What Every Computer Scientist Should Know about Floating Point Arithmetic.

    RonL
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Quote Originally Posted by mHadad
    how can a number that is raised by the power of 2 be negative ,i mean how can i^2 = -1 (can u show me a real world example where i^2 = - 1 so i can understand it more)?
    thanks again captain jack
    We introduce an ideal element i into the number system so that i^2=-1,
    then develop the idea from there.

    I can no more point to a complex or imaginary number than I can point
    to the integer 7. These are mathematical constructs and are judged by
    their usefullness (and/or interest) within mathematics and/or its
    applications.

    Complex numbers were originally introduced because they were usefully
    when finding the real roots of cubics, and today they are used
    in vast tracts of mathematics. They are also interesting in their own right
    and further development of the ideas have been fruitfully in all sorts of ways.

    In real life a spend a lot of my time working with signal processing
    algorithms, and these would be considerably more difficult to handle
    without the use of the complex representation of signals.

    RonL
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Newbie
    Joined
    Sep 2006
    Posts
    22
    thanks alot RonL ,these were great information
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Global Moderator

    Joined
    Nov 2005
    From
    New York City
    Posts
    10,616
    Thanks
    9
    Quote Originally Posted by mHadad
    negative ,i mean how can i^2 = -1 (can u show me a real world example where i^2 = - 1 so i can understand it more)?
    Name a real world problem that uses -5? Same idea -5 does not really exists in "the real world". But you still use it. There are several examples in electricity where this number is used. Another excellent place is in calculus. Sometimes it is easier to do calculus using this number to simplify your work.
    If you are curious there is a further extension to the number "i". Called j and k. The system they compose are called the "quaternions". They are even stranger in the sense that ij\not = ji. But these too also have real world applications.
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Newbie
    Joined
    Sep 2006
    Posts
    22
    well as i know about Digital Signal Processing as i'm yet a begginer in that science that i have seen a usage for complex numbers where they call it ,the imaginary part.i think it was used in convolution.but what i meant by a real world example is that u raise a unit of time by the power of 2 then take the square root of it so it can not be negative or you subtract one point from another in a coordinate plane then raise the result by 2 then take the square root of it to get the absolute value ,like in the distance formula:
    d(a,b) = sqrt. ( ( x2 - x1 ) ^ 2 + ( y2 - y1 ) ^ 2 )
    but i can not say that i can understand a real world incident by i^2 = -1 ,unless it means something like the following : imagine a rubber band that is held between the two fingers for example.if i apply a pressure againset it ,as i'm increasing my pressure it's resistance(the rubber band) will decrease (to a certain point ,which is denoted by the negative number for example).mmm that what came into my mind while typing ,don't know if it holds true or not because what if i increase the pressure againset this rubber band then what is the power of i and does it have to continue to be negative?
    correct me if i'm wrong.
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,664
    Thanks
    298
    Awards
    1
    Quote Originally Posted by mHadad
    well as i know about Digital Signal Processing as i'm yet a begginer in that science that i have seen a usage for complex numbers where they call it ,the imaginary part.i think it was used in convolution.but what i meant by a real world example is that u raise a unit of time by the power of 2 then take the square root of it so it can not be negative or you subtract one point from another in a coordinate plane then raise the result by 2 then take the square root of it to get the absolute value ,like in the distance formula:
    d(a,b) = sqrt. ( ( x2 - x1 ) ^ 2 + ( y2 - y1 ) ^ 2 )
    but i can not say that i can understand a real world incident by i^2 = -1 ,unless it means something like the following : imagine a rubber band that is held between the two fingers for example.if i apply a pressure againset it ,as i'm increasing my pressure it's resistance(the rubber band) will decrease (to a certain point ,which is denoted by the negative number for example).mmm that what came into my mind while typing ,don't know if it holds true or not because what if i increase the pressure againset this rubber band then what is the power of i and does it have to continue to be negative?
    correct me if i'm wrong.
    I can't speak to your example, but energy loss due to resistive forces like friction can often be modelled using "i." A common example of this is in optics where the index of refraction takes a real and complex part, the complex part indicating the amount of loss of intensity of the light as it passes through the material.

    -Dan
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] real world example
    Posted in the Calculus Forum
    Replies: 2
    Last Post: January 9th 2012, 12:06 PM
  2. Real World Algebra Problem!
    Posted in the Business Math Forum
    Replies: 2
    Last Post: December 17th 2011, 07:46 PM
  3. Real World Problem
    Posted in the Algebra Forum
    Replies: 1
    Last Post: September 15th 2009, 10:50 AM
  4. Math in the real world
    Posted in the Algebra Forum
    Replies: 2
    Last Post: January 19th 2009, 03:26 AM
  5. Integration in the real world
    Posted in the Calculus Forum
    Replies: 2
    Last Post: December 2nd 2006, 07:06 AM

Search Tags


/mathhelpforum @mathhelpforum