Ignoring a set of values

Question

Ethan Boyce 2020-8-26

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/584930-ignoring-a-set-of-values

评论： Ethan Boyce 2020-8-26

I need to ignore the second values returned for my subsequent functions. In other words, for the values of t_max, I need to keep 10.27 and ignore 129.72

close all
clear all
syms t b r;
%Profit equation
P = (200+b*t)*(0.65-0.01*r*t+0.00004*t^2)-0.45*t;
%Best time to sell 
dPdt = simplify(vpa(diff(P, t)))
sym_t_max =simplify(vpa(solve(diff(P, t), t)))
t_max = simplify(subs(sym_t_max, {b, r}, {5,1}))
P_max = simplify(subs(P, {t,b,r}, {t_max, 5,1}))

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Answer 1

esat gulhan 2020-8-26

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/584930-ignoring-a-set-of-values#answer_485417

在 MATLAB Online 中打开

Try this

close all
clear all
syms t b r;
%Profit equation
P = (200+b*t)*(0.65-0.01*r*t+0.00004*t^2)-0.45*t;
%Best time to sell 
dPdt = simplify(vpa(diff(P, t)));
sym_t_max =simplify(vpa(solve(diff(P, t), t)));
t_max = simplify(subs(sym_t_max, {b, r}, {5,1}));
P_max = simplify(subs(P, {t,b,r}, {t_max, 5,1}));
t_max(1)
P_max(1)