# New to Matlab, need help

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Christopher 2013-12-17

Hi,
I'm really new to Matlab and I need some help with my homework. We are supposed to write a script/program that determines the zeros of a second degree polynomial function.
All I have so far is the basic structure:
a=input('Koeffizient a: ');
b=input('Koeffizient b: ');
c=input('Koeffizient c: ');
d=b^2-4ac
if d>0
x1=(-b+d)/2a;
x2=(-b-d)/2a;
if d=0
-(b/2a)
d<0
Fehler
end
end
disp('Nullstelle ist: ')
I would appreciate any help (especially those in the form of pointers to help me solve the problem myself and not get you guys to do my homework :P )

### 采纳的回答

kei hin 2013-12-17

Operators can't be omitted. If 'a=2', you want '4',then you need '2*a', not '2a'. And you'd better type your code in Matlab, you will see the tips or warning message from the Matlab to correct your code.
for 'disp' help
You can also type 'doc' in matlab command window, then search something you want to know.
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Walter Roberson 2013-12-17
Remember to include () if needed. You probably want to divide by (2*a) rather than to divide by 2 and then multiply the result by a.

### 更多回答（1 个）

Christopher 2013-12-17

I've worked on it a little more, but my main problem seems to be around the d>=0 part. Any tips?
if true
% code
end
a=input('Koeffizient a eintippen: ');
b=input('Koeffizient b eintippen: ');
c=input('Koeffizient c eintippen: ');
d=(b*b)-(4*a*c);
if d>=0
x1=(-b+d)/(2*a);
if x1 ~=0;
disp (x1)
disp('ist eine Nullstelle');
end
x2=(-b-d)/(2*a);
if x2 ~=0;
disp (x2)
disp('ist eine Nullstelle');
end
x3=-(b/(2*a));
if x3 ~=0;
disp (x3)
disp('ist eine Nullstelle');
end
else disp ('keine Loesung')
end
##### 1 个评论显示 无隐藏 无
kei hin 2013-12-19
what do you want?

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