Why calculation with using matrix is different from manual calculation?

Question

MinWoo Nam 2020-5-18

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/526310-why-calculation-with-using-matrix-is-different-from-manual-calculation

评论： MinWoo Nam 2020-5-18

Re=10^5:10^5:10^6;
C_D = 24./Re + (2.6.*(Re./5))/(1+(Re./5.0).^(1.52))+(0.411*(Re./263000).^(-7.94))./(1+(Re./263000).^(-8))+(0.25*Re./(10^6))/(1+Re./(10^6))

the result above the code is

C_D =
    0.4871    0.4629    0.2064    0.1135    0.1017    0.0998    0.0994    0.0993    0.0992    0.0992

In this code, when Re is 10^6, C_D is 0.0992.

But, I calculate Re=10^6 in manual

the result of C_D value is 0.1296

    >> Re=10^6
Re =
     1000000
>> C_D = 24./Re + (2.6.*(Re./5))/(1+(Re./5.0).^(1.52))+(0.411*(Re./263000).^(-7.94))./(1+(Re./263000).^(-8))+(0.25*Re./(10^6))/(1+Re./(10^6))
C_D =
    0.1296

Why this problem happen?

And can I solve this problem?

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Answer 1

KSSV 2020-5-18

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/526310-why-calculation-with-using-matrix-is-different-from-manual-calculation#answer_433092

编辑：KSSV 2020-5-18

在 MATLAB Online 中打开

YOu have missed . in some places, check the below corrected line:

Re=10^5:10^5:10^6;
C_D = 24./Re + (2.6*(Re/5))./(1+(Re/5.0).^(1.52))+(0.411*(Re/263000).^(-7.94))./(1+(Re/263000).^(-8))+(0.25*Re/(10^6))./(1+Re/(10^6)) ;