How to Input a value, get a result, input that result to calculate another value

Question

RetiredCheetoXI 2022-2-7

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1644895-how-to-input-a-value-get-a-result-input-that-result-to-calculate-another-value

回答： Prahlad Gowtham Katte 2022-2-18

The input is time, which then calculates altitude. This value for altitude is then used to get a value for temperature. How do I make this work? The bolded text is what I just added to it and is not working, everything else works on its own.

prompt = 'Time of flight? (s) ';

t = input(prompt);

tx = t-200:t+200;

if (t <= 45)

h = @(x) 15*x.^2;

fprintf('Altitude: %dm\n\n', h(t))

v = @(x) 30*x;

fprintf('Velocity: %dm/s\n\n', v(t));

if (h <= 11000)

T = (h - 44332.30769230768) / -153.84615384615378;

elseif (h <= 25000)

T = 216.66;

elseif (h <= 47000)

T = (h + 47220) / 333.3;

elseif (h <= 53000)

T = 282.66;

elseif (h <= 79000)

T = (h - 115813) / -222.2;

elseif (h <= 90000)

T = 165.66;

elseif (h <= 110000)

T = (h - 48585) / 250;

end

figure(1)

subplot(2,1,1)

plot(t,h(t),'o',tx,h(tx)), xlabel('Time (s)'), ylabel('Altitude (m)'), title('Altitude vs Time')

subplot(2,1,2)

plot(t,v(t),'o',tx,v(tx)), xlabel('Time (s)'), ylabel('Velocity (m/s)'), title('Velocity vs Time')

elseif (t < 117.5)

h = @(x) 30375 + (1350*x) + 0.5*(-11.5)*x.^2;

fprintf('Altitude: %dm\n\n', h(t))

v = @(x) 1350 - 11.5*x;

fprintf('Velocity: %dm/s\n\n', v(t));

if (h <= 11000)

T = (h - 44332.30769230768) / -153.84615384615378;

elseif (h <= 25000)

T = 216.66;

elseif (h <= 47000)

T = (h + 47220) / 333.3;

elseif (h <= 53000)

T = 282.66;

elseif (h <= 79000)

T = (h - 115813) / -222.2;

elseif (h <= 90000)

T = 165.66;

elseif (h <= 110000)

T = (h - 48585) / 250;

end

figure(2)

subplot(2,1,1)

plot(t,h(t),'o',tx,h(tx)), xlabel('Time (s)'), ylabel('Altitude (m)'), title('Altitude vs Time')

subplot(2,1,2)

plot(t,v(t),'o',tx,v(tx)), xlabel('Time (s)'), ylabel('Velocity (m/s)'), title('Velocity vs Time')

end

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RetiredCheetoXI 2022-2-7

Input a time (t), whcih is then used in a calculation to get altitude (h). This calculated altitude (h) is then used in another calculation to get temperature (T)

Voss 2022-2-8

Replace h with h(t) everywhere in the bolded text.

h is a function. To get h at some given time t, you have to evaluate the function at that time t. That's what h(t) does.

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Answer 1

Prahlad Gowtham Katte 2022-2-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1644895-how-to-input-a-value-get-a-result-input-that-result-to-calculate-another-value#answer_899195

Hello,

As mentioned in the comments please change h to h(t) wherever you are using assignment and comparison operators.

The errors which you got are due to "h" as it is a function handle and it cannot be used in comparison and arithmetic operations but h(t) is a return value of type double which can be used.

For more information on function handles please refer to the following link

https://www.mathworks.com/help/matlab/ref/function_handle.html?

Hope it helps.