h.sum

强大的数学工具包

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        "sum"
        SYNTAX: sum(x=l, u, exp)
                sum(l, u, exp)


        l and u are expressions whose values are integers.
        Remark: If u is an expression containing x (or @), u is 
                evaluated once at the beginning and remains fixed.
   
        exp is an expression whose value is an element of Z, Q, R, C, Z/mZ, 
        GF(p^n), number fields, a polynomial over Z, Q Z/mZ, GF(p^n), 
        number fields, a rational function over Q, a matrix or a vector over 
        all these structures or a point on the current elliptic curve 
        (specified by "curec").

        sum computes the sum of exp for x=l to u (or @=l to u), the value 
        of x (or @) at the end is u.
	If u<l, the result is 0.
              

        Example 1: (correct)

                sum(a=1,1000,1/a^2)


        Example 2: (correct)

                sum(-3,10,x+@)


        Example 3: (incorrect)

                sum(a=0,5,b=2*a)

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