why is not possible to do the logic also why not display

Question

Milan Sumegi 2018-12-15

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编辑： madhan ravi 2018-12-15

采纳的回答： madhan ravi

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Hi

I dont know why I cant display my logick code also an error message on it as well

>> u=symunit; 
L= input('Lenght of the wind turbine blade in meter: ')*u.m; 
L=unitConvert(L,u.mm); 
W=8500*u.N;  
E=42000 *u.N/u.mm^2; 
I=10*(10^6)*u.mm^4; 
D=vpa((W*L^3)/(8*E*I));
Limit= L*0.1;
if D<=Limit disp('Maximum deflexion is tolerable')
else disp('Maximum deflexion will be exceeded')
end

Lenght of the wind turbine blade in meter: 10

Conversion to logical from sym is not possible.

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Answer 1

madhan ravi 2018-12-15

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https://ww2.mathworks.cn/matlabcentral/answers/435915-why-is-not-possible-to-do-the-logic-also-why-not-display#answer_352560

编辑：madhan ravi 2018-12-15

在 MATLAB Online 中打开

P.S - you get an error because L is of symbolic class because you have added (u.mm) unit which belongs symbolic math toolbox , just the numerical value should be used in the if statement , lookup removeUnits() but I guess it works only for user defined functions not for predefined functions.

You need to add tolerance to satisfy the condition because your D is a float number , type floating-point as a tag in this forum to understand more about working with float numbers

if abs(D-Limit)<=1e-4