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The Maxima on-line user's manual

Algebra Calculator

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Nusum Calculator

Nusum

Function: nusum (<expr>, <x>, <i_0>, <i_1>) Carries out indefinite hypergeometric summation of <expr> with respect to <x> using a decision procedure due to R.W. Gosper. <expr> and the result must be expressible as products of integer powers, factorials, binomials, and rational functions.

limit(nusum(i*a**i,i,0,m-1)/a**m,m,infty);

The terms "definite" and "indefinite summation" are used analogously to "definite" and "indefinite integration". To sum indefinitely means to give a symbolic result for the sum over intervals of variable length, not just e.g. 0 to inf. Thus, since there is no formula for the general partial sum of the binomial series, nusum cant do it.

nusum and unsum know a little about sums and differences of finite products. See also unsum.

Examples:

          (%i1) nusum (n*n!, n, 0, n);

          Dependent equations eliminated:  (1)
          (%o1)                     (n + 1)! - 1
          (%i2) nusum (n^4*4^n/binomial(2*n,n), n, 0, n);
                               4        3       2              n
                2 (n + 1) (63 n  + 112 n  + 18 n  - 22 n + 3) 4      2
          (%o2) ------------------------------------------------ - ------
                              693 binomial(2 n, n)                 3 11 7
          (%i3) unsum (%, n);
                                        4  n
                                       n  4
          (%o3)                   ----------------
                                  binomial(2 n, n)
          (%i4) unsum (prod (i^2, i, 1, n), n);
                              n - 1
                              /===\
                               ! !   2
          (%o4)              ( ! !  i ) (n - 1) (n + 1)
                               ! !
                              i = 1
          (%i5) nusum (%, n, 1, n);

Dependent equations eliminated: (2 3) n /===\ ! ! 2

          (%o5)                      ! !  i  - 1
                                     ! !
                                    i = 1

(%o1)                                true
(%i2) 

Nusum Example

Related Examples

nusum

nusum(i*a**i,i,0,m-1);

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nusum

nusum(4**i,i,0,m-1);

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nusum

nusum(4**i,i,0,m-1);

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nusum

lim(nusum(i*a**i,i,0,...

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nusum

nusum(i*a**i,i,0,m-1);

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nusum

nusum(i*2**i,i,0,m-1);

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nusum

nusum(i*i,i,1,n);

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nusum

nusum(i*i*i,i,1,n);

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nusum

nusum(4**i,i,1,m-1);

Calculate