Getting single answer for function with an array

Question

Takura Nyatsuro 2022-4-16

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1698315-getting-single-answer-for-function-with-an-array

编辑： Torsten 2022-4-16

Hi there,

Im trying to plot a graph of Drag against velocity. The velocity(V) in which is stored in an array from 20 to 100 in increments of 10. however when i calculate drag (D) the code only outputs a single output for drag instead of one output for each velocity.

Any help would be appreciated ,

Thank you

>> d=1.225;
>> S=50;
>> Cd=0.03;
>> K=0.04;
>> W=50;
>> V=[20:10:100];
>> D=((0.5)*d*(V.^2)*S*Cd+(K*W^2))/((0.5*d*(V.^2)*S))

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Answer 1

Torsten 2022-4-16

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1698315-getting-single-answer-for-function-with-an-array#answer_944395

在 MATLAB Online 中打开

D=(0.5*d*V.^2*S*Cd+K*W^2)./(0.5*d*V.^2*S)

instead of

D=((0.5)*d*(V.^2)*S*Cd+(K*W^2))/((0.5*d*(V.^2)*S))

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Voss 2022-4-16

编辑：Voss 2022-4-16

在 MATLAB Online 中打开

./ is element-wise division:

[2 4 6 8]./[2 3 4 5] % = [2/2 4/3 6/4 8/5]
ans = 1×4
    1.0000    1.3333    1.5000    1.6000

/ is matrix division:

[2 4 6 8]/[2 3 4 5]
ans = 1.4815

More information: https://www.mathworks.com/help/matlab/matlab_prog/array-vs-matrix-operations.html

Torsten 2022-4-16

编辑：Torsten 2022-4-16

@Takura Nyatsuro

Since you already used elementwise multiplication for V, I didn't explain in detail what was the reason for the error. I thought it was only an oversight.

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