필터 지우기
필터 지우기

Why loop is not being excluded with the given condition?

조회 수: 1 (최근 30일)
I am using the continue function to exclude the nodes of a sine function in matlab. When I start from 0, it is excluding all the nodes. However, when I start from 0.1 (for some reasons), it does not exclude the nodes i.e. 1.5, 2.5, 3, 3.5. Can you tell me what can be the reason and how to deal with it?
F_b = 16000; % N
A_b = 125.66; % mm^2
for cycles = 0:0.1:10
if cycles/0.5 == fix(cycles/0.5)
continue
end
disp(cycles)
end
0.1000 0.2000 0.3000 0.4000 0.6000 0.7000 0.8000 0.9000 1.1000 1.2000 1.3000 1.4000 1.6000 1.7000 1.8000 1.9000 2.1000 2.2000 2.3000 2.4000 2.6000 2.7000 2.8000 2.9000 3.1000 3.2000 3.3000 3.4000 3.6000 3.7000 3.8000 3.9000 4.1000 4.2000 4.3000 4.4000 4.6000 4.7000 4.8000 4.9000 5.1000 5.2000 5.3000 5.4000 5.6000 5.7000 5.8000 5.9000 6.1000 6.2000 6.3000 6.4000 6.6000 6.7000 6.8000 6.9000 7.1000 7.2000 7.3000 7.4000 7.6000 7.7000 7.8000 7.9000 8.1000 8.2000 8.3000 8.4000 8.6000 8.7000 8.8000 8.9000 9.1000 9.2000 9.3000 9.4000 9.6000 9.7000 9.8000 9.9000
The other is
F_b = 16000; % N
A_b = 125.66; % mm^2
for cycles = 0.1:0.1:10
if cycles/0.5 == fix(cycles/0.5)
continue
end
disp(cycles)
end
0.1000 0.2000 0.3000 0.4000 0.6000 0.7000 0.8000 0.9000 1.1000 1.2000 1.3000 1.4000 1.5000 1.6000 1.7000 1.8000 1.9000 2.1000 2.2000 2.3000 2.4000 2.5000 2.6000 2.7000 2.8000 2.9000 3.0000 3.1000 3.2000 3.3000 3.4000 3.5000 3.6000 3.7000 3.8000 3.9000 4.1000 4.2000 4.3000 4.4000 4.6000 4.7000 4.8000 4.9000 5.1000 5.2000 5.3000 5.4000 5.6000 5.7000 5.8000 5.9000 6.1000 6.2000 6.3000 6.4000 6.6000 6.7000 6.8000 6.9000 7.1000 7.2000 7.3000 7.4000 7.6000 7.7000 7.8000 7.9000 8.1000 8.2000 8.3000 8.4000 8.6000 8.7000 8.8000 8.9000 9.1000 9.2000 9.3000 9.4000 9.6000 9.7000 9.8000 9.9000
Thanks for the help in advance.
Regards,
Muhammad Hassaan Bin Tariq
  댓글 수: 2
Stephen23
Stephen23 2022년 10월 18일
"Can you tell me what can be the reason..."
Because 0.1 cannot be exactly stored in a binary floating point number (in exactly the same way that you cannot write 1/3 exactly on a piece of paper using a decimal fraction). The floating point error accumulates differently in the COLON operator, depending on the provided values. Lets compare:
cycles0 = 0:0.1:10;
cycles1 = 0.1:0.1:10;
fprintf('%.40f\n', cycles0(16)/0.5, fix(cycles0(16)/0.5), cycles1(15)/0.5, fix(cycles1(15)/0.5))
3.0000000000000000000000000000000000000000 3.0000000000000000000000000000000000000000 3.0000000000000004440892098500626161694527 3.0000000000000000000000000000000000000000
"...and how to deal with it?"
Either:
  • work with integers, or
  • use tolerances when comparing (i.e. do not use exact equality), avoid FIX, etc.
Your current approach is numerically fragile and should be avoided.
Muhammad Hassaan Bin Tariq
Muhammad Hassaan Bin Tariq 2022년 10월 18일
I got your point but why is it avoiding higher points with the same fix command? I mean it is excluding 7, 7.5, 8 etc.
It is a long code. Well the mod() operation is working well.
Thanks for your help very much.
Regards

댓글을 달려면 로그인하십시오.

채택된 답변

Tobias Panitz
Tobias Panitz 2022년 10월 18일
Hey,
have you tried using the modulus function?
if mod(cycles,0.5) == 0
continue;
end

추가 답변 (0개)

카테고리

Help CenterFile Exchange에서 Loops and Conditional Statements에 대해 자세히 알아보기

제품


릴리스

R2022a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by