My graph is blank

5 次查看（过去 30 天）
Adeola Badejo
Adeola Badejo 2020-6-4
评论： KSSV 2020-6-4
ive written a code and the numbers on the x and y axis show up but im not getting any actual plots.
w = input('Enter weight "W" of aircraft value(kg)');
c_d0 = input('Enter profile drag coefficient "C_d0" of aircraft value');
s = input('Enter wing span "S" of aircraft value(m)');
p_0 = input('Enter initial power at sea level "P_0" of aircraft engine value(W)');
k = input('Enter induced drag coefficient "K" of aircraft value');
rho_0 = 1.225;
h=0:0.1:20;
for i=1:length(h)
sigma(i)=20-h(i)/20+h(i);
a=c_d0*0.5*rho_0*s;
b=-p_0;
c=k*w^2/0.5*rho_0*sigma(i).^2*s;
y=[a 0 0 b c];
r=roots(y);
end
plot(r(3),h,r(4),h)
  2 个评论
KSSV
KSSV 2020-6-4
h happens to be a vector, and r(3) , r(4) are scalars......you cannot plot like that.
Adeola Badejo
Adeola Badejo 2020-6-4
i see so how would you suggest i fix it?

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

KSSV
KSSV 2020-6-4
w = input('Enter weight "W" of aircraft value(kg)');
c_d0 = input('Enter profile drag coefficient "C_d0" of aircraft value');
s = input('Enter wing span "S" of aircraft value(m)');
p_0 = input('Enter initial power at sea level "P_0" of aircraft engine value(W)');
k = input('Enter induced drag coefficient "K" of aircraft value');
rho_0 = 1.225;
h=0:0.1:20;
r3 = zeros(size(h)) ;
r4 = zeros(size(h)) ;
for i=1:length(h)
sigma(i)=20-h(i)/20+h(i);
a=c_d0*0.5*rho_0*s;
b=-p_0;
c=k*w^2/0.5*rho_0*sigma(i).^2*s;
y=[a 0 0 b c];
r=roots(y);
r3(i) = y(3) ;
r4(i) = y(4) ;
end
plot(r3,h,r4,h)
  4 个评论
显示 2更早的评论
Adeola Badejo
Adeola Badejo 2020-6-4
the problem is to plot a graph of the minimum and maximum roots against h whichould give me a parabola but instead gives me a straight line so i must have gone wrong somewhere
KSSV
KSSV 2020-6-4
You can get min and max using:
r3(i) = min(y) ;
r4(i) = max(y) ;
You need to rethink on your code.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Construction 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by