Properties of greatest integer function

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I am curious to know some properties of the floor functions, for instance, $lfloor a cdot x rfloor$, $lfloor a1cdot x1+a2cdot x2 rfloor$, etc. Is there any book that contains such properties ?










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  • What kind of properties are you looking for?
    – AD.
    Jun 28 '15 at 10:06










  • For example, is it true that floor(ax) = afloor(x) for non-negative real number a ? What can you tell if a is negative real ?
    – Naveen Crasta
    Jun 28 '15 at 12:55










  • There is no such rule, as easy examples shows, please try to find some and you will see why.
    – AD.
    Jun 28 '15 at 17:39














up vote
0
down vote

favorite












I am curious to know some properties of the floor functions, for instance, $lfloor a cdot x rfloor$, $lfloor a1cdot x1+a2cdot x2 rfloor$, etc. Is there any book that contains such properties ?










share|cite|improve this question























  • What kind of properties are you looking for?
    – AD.
    Jun 28 '15 at 10:06










  • For example, is it true that floor(ax) = afloor(x) for non-negative real number a ? What can you tell if a is negative real ?
    – Naveen Crasta
    Jun 28 '15 at 12:55










  • There is no such rule, as easy examples shows, please try to find some and you will see why.
    – AD.
    Jun 28 '15 at 17:39












up vote
0
down vote

favorite









up vote
0
down vote

favorite











I am curious to know some properties of the floor functions, for instance, $lfloor a cdot x rfloor$, $lfloor a1cdot x1+a2cdot x2 rfloor$, etc. Is there any book that contains such properties ?










share|cite|improve this question















I am curious to know some properties of the floor functions, for instance, $lfloor a cdot x rfloor$, $lfloor a1cdot x1+a2cdot x2 rfloor$, etc. Is there any book that contains such properties ?







special-functions






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edited Jun 28 '15 at 23:48









iadvd

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asked Jun 26 '15 at 21:30









Naveen Crasta

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  • What kind of properties are you looking for?
    – AD.
    Jun 28 '15 at 10:06










  • For example, is it true that floor(ax) = afloor(x) for non-negative real number a ? What can you tell if a is negative real ?
    – Naveen Crasta
    Jun 28 '15 at 12:55










  • There is no such rule, as easy examples shows, please try to find some and you will see why.
    – AD.
    Jun 28 '15 at 17:39
















  • What kind of properties are you looking for?
    – AD.
    Jun 28 '15 at 10:06










  • For example, is it true that floor(ax) = afloor(x) for non-negative real number a ? What can you tell if a is negative real ?
    – Naveen Crasta
    Jun 28 '15 at 12:55










  • There is no such rule, as easy examples shows, please try to find some and you will see why.
    – AD.
    Jun 28 '15 at 17:39















What kind of properties are you looking for?
– AD.
Jun 28 '15 at 10:06




What kind of properties are you looking for?
– AD.
Jun 28 '15 at 10:06












For example, is it true that floor(ax) = afloor(x) for non-negative real number a ? What can you tell if a is negative real ?
– Naveen Crasta
Jun 28 '15 at 12:55




For example, is it true that floor(ax) = afloor(x) for non-negative real number a ? What can you tell if a is negative real ?
– Naveen Crasta
Jun 28 '15 at 12:55












There is no such rule, as easy examples shows, please try to find some and you will see why.
– AD.
Jun 28 '15 at 17:39




There is no such rule, as easy examples shows, please try to find some and you will see why.
– AD.
Jun 28 '15 at 17:39










1 Answer
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  • There is Legendre's formula which counts the number of positive integers less than or equal to a number $n$ which are not divisible by any of the first $k$ primes:
    $$beginalign
    &phi(n,k)=lfloor n rfloor-sum_p_ile kleftlfloor dfrac n (p_i)rightrfloor+sum_p_i<p_jle kleftlfloordfrac n(p_ip_j)rightrfloor-sum_p_i<p_j<p_mle kleftlfloor dfracn(p_ip_jp_m)rightrfloor+dots
    endalign$$

which tells us that total number of times a prime $p$ divides $n!$ is $$sum_k=1^inftylfloorfracnp^krfloor$$



  • For positive integers $lfloor sqrtn+sqrtn+1rfloor=lfloorsqrt4n+2rfloor$

  • $lfloor2xrfloor+lfloor2yrfloorge lfloor x rfloor+lfloor y rfloor+lfloor x+y rfloor$

  • $lfloor frac n2 rfloor- lfloor frac-n2 rfloor=n$ for integers $n ge 0$.

You should look up in books on Discrete mathematics or combinatorics. Also see wikipedia link






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    • There is Legendre's formula which counts the number of positive integers less than or equal to a number $n$ which are not divisible by any of the first $k$ primes:
      $$beginalign
      &phi(n,k)=lfloor n rfloor-sum_p_ile kleftlfloor dfrac n (p_i)rightrfloor+sum_p_i<p_jle kleftlfloordfrac n(p_ip_j)rightrfloor-sum_p_i<p_j<p_mle kleftlfloor dfracn(p_ip_jp_m)rightrfloor+dots
      endalign$$

    which tells us that total number of times a prime $p$ divides $n!$ is $$sum_k=1^inftylfloorfracnp^krfloor$$



    • For positive integers $lfloor sqrtn+sqrtn+1rfloor=lfloorsqrt4n+2rfloor$

    • $lfloor2xrfloor+lfloor2yrfloorge lfloor x rfloor+lfloor y rfloor+lfloor x+y rfloor$

    • $lfloor frac n2 rfloor- lfloor frac-n2 rfloor=n$ for integers $n ge 0$.

    You should look up in books on Discrete mathematics or combinatorics. Also see wikipedia link






    share|cite|improve this answer
























      up vote
      0
      down vote













      • There is Legendre's formula which counts the number of positive integers less than or equal to a number $n$ which are not divisible by any of the first $k$ primes:
        $$beginalign
        &phi(n,k)=lfloor n rfloor-sum_p_ile kleftlfloor dfrac n (p_i)rightrfloor+sum_p_i<p_jle kleftlfloordfrac n(p_ip_j)rightrfloor-sum_p_i<p_j<p_mle kleftlfloor dfracn(p_ip_jp_m)rightrfloor+dots
        endalign$$

      which tells us that total number of times a prime $p$ divides $n!$ is $$sum_k=1^inftylfloorfracnp^krfloor$$



      • For positive integers $lfloor sqrtn+sqrtn+1rfloor=lfloorsqrt4n+2rfloor$

      • $lfloor2xrfloor+lfloor2yrfloorge lfloor x rfloor+lfloor y rfloor+lfloor x+y rfloor$

      • $lfloor frac n2 rfloor- lfloor frac-n2 rfloor=n$ for integers $n ge 0$.

      You should look up in books on Discrete mathematics or combinatorics. Also see wikipedia link






      share|cite|improve this answer






















        up vote
        0
        down vote










        up vote
        0
        down vote









        • There is Legendre's formula which counts the number of positive integers less than or equal to a number $n$ which are not divisible by any of the first $k$ primes:
          $$beginalign
          &phi(n,k)=lfloor n rfloor-sum_p_ile kleftlfloor dfrac n (p_i)rightrfloor+sum_p_i<p_jle kleftlfloordfrac n(p_ip_j)rightrfloor-sum_p_i<p_j<p_mle kleftlfloor dfracn(p_ip_jp_m)rightrfloor+dots
          endalign$$

        which tells us that total number of times a prime $p$ divides $n!$ is $$sum_k=1^inftylfloorfracnp^krfloor$$



        • For positive integers $lfloor sqrtn+sqrtn+1rfloor=lfloorsqrt4n+2rfloor$

        • $lfloor2xrfloor+lfloor2yrfloorge lfloor x rfloor+lfloor y rfloor+lfloor x+y rfloor$

        • $lfloor frac n2 rfloor- lfloor frac-n2 rfloor=n$ for integers $n ge 0$.

        You should look up in books on Discrete mathematics or combinatorics. Also see wikipedia link






        share|cite|improve this answer












        • There is Legendre's formula which counts the number of positive integers less than or equal to a number $n$ which are not divisible by any of the first $k$ primes:
          $$beginalign
          &phi(n,k)=lfloor n rfloor-sum_p_ile kleftlfloor dfrac n (p_i)rightrfloor+sum_p_i<p_jle kleftlfloordfrac n(p_ip_j)rightrfloor-sum_p_i<p_j<p_mle kleftlfloor dfracn(p_ip_jp_m)rightrfloor+dots
          endalign$$

        which tells us that total number of times a prime $p$ divides $n!$ is $$sum_k=1^inftylfloorfracnp^krfloor$$



        • For positive integers $lfloor sqrtn+sqrtn+1rfloor=lfloorsqrt4n+2rfloor$

        • $lfloor2xrfloor+lfloor2yrfloorge lfloor x rfloor+lfloor y rfloor+lfloor x+y rfloor$

        • $lfloor frac n2 rfloor- lfloor frac-n2 rfloor=n$ for integers $n ge 0$.

        You should look up in books on Discrete mathematics or combinatorics. Also see wikipedia link







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        answered Jun 29 '15 at 0:12









        Bhaskar Vashishth

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