class quaternion:
def __init__(self, a, b, c, d):
self.R = float(a) # real part
self.I = float(b) # first imaginary part
self.J = float(c) # second imaginary part
self.K = float(d) # third imaginary part
def normalize(self):
n = self.norm()
qret = quaternion(self.R, self.I, self.J, self.K)
if n == 0:
print 'cant normalize, is 0'
else:
qret.R = self.R/n # real part
qret.I = self.I/n # first imaginary part
qret.J = self.J/n # second imaginary part
qret.K = self.K/n # third imaginary part
return qret
return quaternion(a, b, c, d)

how to define a function that have a class as return ?

Use the class name as return type.

abbl1 schrieb:

and what is the meaning of this self and how can we get the same meaning on a c++ code ?

By convention, self is the usual name for the first method parameter, which is a reference to the instance used for the method call. It is used to access the class instance's data attributes. In C++, you don't need it.

class quaternion {

float R,I,J,K;

public:

quaternion (float,float,float,float);

quaternion normalize() {

n=norm();
qret=quaternion(R,I,J,K);
qret.R=R/n;
qret.I=I/n;
qret.J=J/n;
qret.K=K/n;
return qret;
}

By convention, self is the usual name for the first method parameter, which is a reference to the instance used for the method call. It is used to access the class instance's data attributes. In C++, you don't need it.

The equivalent in C++ is named "this".
--> http://www.tutorialspoint.com/cplusplus/cpp_this_pointer.htm

so is that right if i write this for this python code?

- Definition of qret is missing
- quaternion constructor definition is missing
- You're not checking for n==0

float R,I,J,K;
public:

quaternion (float a ,float b ,float c ,float d ) {

R=a; I=b; J=c; K=d; }
quaternion normalize() {

quaternion qret;
float n;

n=norm();
qret=quaternion(R,I,J,K);
qret.R=R/n;
qret.I=I/n;
qret.J=J/n;
qret.K=K/n;
return qret;
}
} return quaternion(a, b, c, d);
(forget about the n==0 )

Do you want to be as close to the Python code as possible, or do you want good C++?
Do you want code that works? Because right now your C++ code won't work, just like the Python code.

And after considering this, it's beginning to smell distinctively like homework.

Let me make another observation: the code you posted with the question if it's OK, doesn't even compile. What do you want to do with a piece of code, if you cannot even compile it?
And then the phrase "just one last check". One last check before ... what?

So you tell me: If this doesn't smell like homework, then what does?

I will however not interfere if anyone wants to help you - aside from making my "observations" that is.

----

That aside...
Maybe you should start with settings up a development environment where you can compile and run C++ code.
The chances of learning C++, even just "a little bit", without a working development environment, are close to zero.