Loop Trough Time t = t+dt
3 ビュー (過去 30 日間)
古いコメントを表示
I have a simple code like this
t = 1380;
dt = 0.1
for i = 1:1000
t = t+dt;
disp(t)
end
I believe the answer should be obvious that the final answer should be
t = 1480. I dont know why Matlab shows the answer a little bit different which is 1479.99999999991.
Anyone know why?
0 件のコメント
回答 (1 件)
Star Strider
2019 年 11 月 13 日
You have encountered floating-point approximation error.
3 件のコメント
Star Strider
2019 年 11 月 18 日
Yes.
Change it to:
if abs(t - 1400) < 0.05
a = 2
end
Since the code counts up by ‘dt’, this will introduce a tolerance in the calculation, so the floating-point approximation error are taken into account.
To see this graphically:
t = linspace(1399, 1401);
figure
plot(t, (abs(t - 1400) < 0.05))
grid
That will show the effect of using the inequality to test for a range of values for ‘t’ near 1400.
Experiment to get the result you want.
darova
2019 年 11 月 18 日
Don't use equal sign for float numbers
if abs(t-1400) < 1e-6 % tolerance
a = 2;
end
参考
カテゴリ
Help Center および File Exchange で Loops and Conditional Statements についてさらに検索
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!