'Gauss's Algorithm' for computing modular fractions and inverses












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$begingroup$


There is an answer on the site for solving simple linear congruences via so called 'Gauss's Algorithm' presented in a fractional form. Answer was given by Bill Dubuque and it was said that the fractional form is essentially Gauss, Disquisitiones Arithmeticae, Art. 13, 1801.



Now I have studied the article from the book, but I am not seeing the connection to the fractional form. What Gauss does is reducing $b$ via $p$ mod $b = p - qb$ and I do not see that happening in the fractional form nor do I see how it computes an inverse. I have already talked with Bill about this via comments, but decided to open a new question so he or anyone else can help me more intuitively understand what is going on here. This article is supposed to give an algorithm to compute inverses in a prime modulus, yet I have no idea how.



Edit:
Bill when you see this(I know you will :) ) please try to do this very detailed explaining everything. I am very new to number theory and there might be others so we thoroughly understand what exactly goes on here.










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$endgroup$








  • 1




    $begingroup$
    I will answer later when I have more spare time. Others who may be interested in answering can learn the detailed context from the "via comments" link above.
    $endgroup$
    – Bill Dubuque
    Jan 2 at 17:02












  • $begingroup$
    Ok, though it might be best that you do it. You named the algorithm after all.
    $endgroup$
    – Michael Munta
    Jan 3 at 9:57










  • $begingroup$
    If you could do it this weekend please, I am really anxious to understand this :)
    $endgroup$
    – Michael Munta
    Jan 4 at 10:25
















3












$begingroup$


There is an answer on the site for solving simple linear congruences via so called 'Gauss's Algorithm' presented in a fractional form. Answer was given by Bill Dubuque and it was said that the fractional form is essentially Gauss, Disquisitiones Arithmeticae, Art. 13, 1801.



Now I have studied the article from the book, but I am not seeing the connection to the fractional form. What Gauss does is reducing $b$ via $p$ mod $b = p - qb$ and I do not see that happening in the fractional form nor do I see how it computes an inverse. I have already talked with Bill about this via comments, but decided to open a new question so he or anyone else can help me more intuitively understand what is going on here. This article is supposed to give an algorithm to compute inverses in a prime modulus, yet I have no idea how.



Edit:
Bill when you see this(I know you will :) ) please try to do this very detailed explaining everything. I am very new to number theory and there might be others so we thoroughly understand what exactly goes on here.










share|cite|improve this question











$endgroup$








  • 1




    $begingroup$
    I will answer later when I have more spare time. Others who may be interested in answering can learn the detailed context from the "via comments" link above.
    $endgroup$
    – Bill Dubuque
    Jan 2 at 17:02












  • $begingroup$
    Ok, though it might be best that you do it. You named the algorithm after all.
    $endgroup$
    – Michael Munta
    Jan 3 at 9:57










  • $begingroup$
    If you could do it this weekend please, I am really anxious to understand this :)
    $endgroup$
    – Michael Munta
    Jan 4 at 10:25














3












3








3





$begingroup$


There is an answer on the site for solving simple linear congruences via so called 'Gauss's Algorithm' presented in a fractional form. Answer was given by Bill Dubuque and it was said that the fractional form is essentially Gauss, Disquisitiones Arithmeticae, Art. 13, 1801.



Now I have studied the article from the book, but I am not seeing the connection to the fractional form. What Gauss does is reducing $b$ via $p$ mod $b = p - qb$ and I do not see that happening in the fractional form nor do I see how it computes an inverse. I have already talked with Bill about this via comments, but decided to open a new question so he or anyone else can help me more intuitively understand what is going on here. This article is supposed to give an algorithm to compute inverses in a prime modulus, yet I have no idea how.



Edit:
Bill when you see this(I know you will :) ) please try to do this very detailed explaining everything. I am very new to number theory and there might be others so we thoroughly understand what exactly goes on here.










share|cite|improve this question











$endgroup$




There is an answer on the site for solving simple linear congruences via so called 'Gauss's Algorithm' presented in a fractional form. Answer was given by Bill Dubuque and it was said that the fractional form is essentially Gauss, Disquisitiones Arithmeticae, Art. 13, 1801.



Now I have studied the article from the book, but I am not seeing the connection to the fractional form. What Gauss does is reducing $b$ via $p$ mod $b = p - qb$ and I do not see that happening in the fractional form nor do I see how it computes an inverse. I have already talked with Bill about this via comments, but decided to open a new question so he or anyone else can help me more intuitively understand what is going on here. This article is supposed to give an algorithm to compute inverses in a prime modulus, yet I have no idea how.



Edit:
Bill when you see this(I know you will :) ) please try to do this very detailed explaining everything. I am very new to number theory and there might be others so we thoroughly understand what exactly goes on here.







elementary-number-theory






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 2 at 17:01









Bill Dubuque

209k29190633




209k29190633










asked Jan 2 at 9:05









Michael MuntaMichael Munta

688




688








  • 1




    $begingroup$
    I will answer later when I have more spare time. Others who may be interested in answering can learn the detailed context from the "via comments" link above.
    $endgroup$
    – Bill Dubuque
    Jan 2 at 17:02












  • $begingroup$
    Ok, though it might be best that you do it. You named the algorithm after all.
    $endgroup$
    – Michael Munta
    Jan 3 at 9:57










  • $begingroup$
    If you could do it this weekend please, I am really anxious to understand this :)
    $endgroup$
    – Michael Munta
    Jan 4 at 10:25














  • 1




    $begingroup$
    I will answer later when I have more spare time. Others who may be interested in answering can learn the detailed context from the "via comments" link above.
    $endgroup$
    – Bill Dubuque
    Jan 2 at 17:02












  • $begingroup$
    Ok, though it might be best that you do it. You named the algorithm after all.
    $endgroup$
    – Michael Munta
    Jan 3 at 9:57










  • $begingroup$
    If you could do it this weekend please, I am really anxious to understand this :)
    $endgroup$
    – Michael Munta
    Jan 4 at 10:25








1




1




$begingroup$
I will answer later when I have more spare time. Others who may be interested in answering can learn the detailed context from the "via comments" link above.
$endgroup$
– Bill Dubuque
Jan 2 at 17:02






$begingroup$
I will answer later when I have more spare time. Others who may be interested in answering can learn the detailed context from the "via comments" link above.
$endgroup$
– Bill Dubuque
Jan 2 at 17:02














$begingroup$
Ok, though it might be best that you do it. You named the algorithm after all.
$endgroup$
– Michael Munta
Jan 3 at 9:57




$begingroup$
Ok, though it might be best that you do it. You named the algorithm after all.
$endgroup$
– Michael Munta
Jan 3 at 9:57












$begingroup$
If you could do it this weekend please, I am really anxious to understand this :)
$endgroup$
– Michael Munta
Jan 4 at 10:25




$begingroup$
If you could do it this weekend please, I am really anxious to understand this :)
$endgroup$
– Michael Munta
Jan 4 at 10:25










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