how to write a function for quadratic equation
显示 更早的评论
I wrote this into matlab but it doesn't work, can someone explain why?
function [x1,x2] = QuadraticEquation (a,b,c)
d=b^2-4*a*c;
if d>=0
disp ('two roots exist')
x1=(-b-sqrt(d))/2*a
x2=(-b+sqrt(d))/2*a
plot(x1,0,'rx',x2,0,'rx')
hold on
x=-10:10
y=a*x.^2+b*x+c
plot(x,y)
hold off
else
disp ('no real roots’)
end
3 个评论
Matt J
2019-12-7
First explain to us why you think it doesn't work.
Alisha Mistry
2019-12-7
Image Analyst
2019-12-7
You need to pass in something. You can't just click the green Run triangle on the toolbar. See Matt J's Answer below.
采纳的回答
[x1,x2] = QuadraticEquation (1,-2,0)
function [x1,x2] = QuadraticEquation (a,b,c)
d=b^2-4*a*c;
if d>=0
disp ('real roots exist')
x1=(-b-sqrt(d))/(2*a); %<---------- brackets in denominator
x2=(-b+sqrt(d))/(2*a); %<---------- brackets in denominator
plot(x1,0,'rx',x2,0,'rx')
hold on
fplot(@(x) a*x.^2+b*x+c) %<---------- fplot is more convenient here
hold off
else
disp ('no real roots') %<---------- missing quote
[x1,x2]=deal([]) %<---------- missing default assignment
end
end
2 个评论
Grady
2024-7-12
This code will not work for me I am using 2024a.
Steven Lord
2024-7-13
What does "will not work" mean in this context?
- Do you receive warning and/or error messages? If so the full and exact text of those messages (all the text displayed in orange and/or red in the Command Window) may be useful in determining what's going on and how to avoid the warning and/or error.
- Does it do something different than what you expected? If so, what did it do and what did you expect it to do?
- Did MATLAB crash? If so please send the crash log file (with a description of what you were running or doing in MATLAB when the crash occured) to Technical Support so we can investigate.
Show us how you tried to use this code as well.
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