please share matlab command please

[parid]

>> syms n x

y = symsum ((1+n^2/n),n,0,100)

y = 5151

[Atsushi Ueno]

syms n x
y = symsum ((1+n^2/n),n,0,100)

y = 

5151

syms n x
y = symsum ((1+n^2)/n,n,0,100) 

Error using symengine
Division by zero.

Error in sym/symsum (line 70)
rSym = mupadmex('symobj::map',fsym.s,'symobj::symsum',x.s,a.s,b.s);

[Walter Roberson]

@Atsushi Ueno

You can avoid the division by 0 error.

syms n
f = (1+n^2)/n

f = 

%break the sum into two parts
part2 = symsum(f, n, 1, 100)

part2 = 

part1 = limit(f, n, 0)

part1 = 

NaN

y = part1 + part2

y = 

NaN

Answer 1

[Walter Roberson]

You can break this up into two sums: one for n = 0 exactly, and the other one for n = 1 to 100.

You can calculate the 1 to 100 using symsum

The value for 0 exactly would normally involve a division by 0, but you can try to approach the problem using limit . Just make sure to compare the limit from the "left" with the limit from the "right"

[parid]

I try in you suggest to me. please help check.

syms n x

y = symsum((1+n^2/n),n,0,100)

y =

5151

[Walter Roberson]

You coded to calculate n^2 and divide by n, and add 1 to the result of the division. But the expression requires you to take n^2 and add 1 to the result, and divide the total by n

Mathematically except at 0 the expression is the same as (1/n)+n

[parid]

>> syms n x

y = symsum ((1+n^2/n),n,0,100)

y = 5151

[Walter Roberson]

Remember that / has higher priority than division, so

1+n^2/n is 1 + (n^2/n)

In turn, ^ has higher priority than / so this is 1 + ((n^2)/n)

But n^2/n is just n unless n is 0 (or unless n is so large that n^2 overflows to infinitity), so that expression is equivalent to 1 + (n)

This is different than taking n^2 and adding 1 to that value, and then dividing the whole thing by n .

Consider for example if n = 2 and n = 5

n = [2 5]

n = 1×2

2 5

result1 = (1+n.^2./n)

result1 = 1×2

3 6

result2 = 1 + ((n.^2)./n)

result2 = 1×2

3 6

temporary = n.^2 + 1; result3 = temporary ./ n

result3 = 1×2

2.5000 5.2000

result1 and result2 are the same -- they are the same calculation. result3 is different: they show what happens when you make sure to do the addition first before the division.