# Help to transform math formula to matlab

조회 수: 1(최근 30일)
Matthew Lima 2021년 11월 14일
댓글: Dave B 2021년 11월 15일
Hello,
I am trying to transform this formula into matlab, but I can't use a for/while loop. X is an array with dimension n and every position receives this sum.
I tried like this, but I couldn't remove the loop here, can I achieve this without a loop?
I also tried to use arrayfun, but without success because every position of the array was receiving the same value.
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Dave B 2021년 11월 14일
Ah I was trying to avoid doing it for you so that you could feel the satisfaction :) Glad it feels simple, hope it stays that way as you delve deeper!
note this is the simplified version of what you wrote:
x = log(1:n) * sum(exp((1:m).^2))

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### 답변(1개)

Sulaymon Eshkabilov 2021년 11월 15일
Using the vectorization:
format long
m=5;
jj=1:m;
XSum1 = sum(log(jj).*exp(jj.^2))
XSum1 =
1.158997425794889e+11
% Or alternatively
Xs = log(jj).*exp(jj.^2);
XSum2=sum(Xs)
XSum2 =
1.158997425794889e+11
% Sum stepby-step:
cumsum(Xs)
ans = 1×5
1.0e+11 * 0 0.000000000378446 0.000000089399921 0.000123277048990 1.158997425794889
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Dave B 2021년 11월 15일
Note that i and j are not the same in the question, the correct answer here is:
x = log(1:n) * sum(exp((1:m).^2))
as discussed in the comments above.

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