# Squared Distance inC3_W2_RecSysNN_Assignment

I am struggling to write a code for squared distance. I have used Numpy function to square the difference . It is not finding square function. I find same issue with tf.

need some help and guidance. I appreciate if any one respond

1 Like

Hello @Sudhir_Nandamuru,

np.square should do the job. If you have imported `numpy` as `np`, then you need to use `np.square`. If you have imported `numpy` without giving it an alias, then `numpy.square`. It is very often that we give it an alias of `np`. Please check the first code cell of the notebook.

``````import numpy as np
np.square(3)
``````
``````import numpy
numpy.square(3)
``````

Cheers,
Raymond

@rmwkwok thanksā¦ I tried to attemp the subtraction first and then square the result. np.square is not recognizedā¦

Does the first cell of your notebook contain `import numpy as np`? If so, can you run it and see if `np.square` can be recognized?

@rmwkwok import numpy as np is first statement and I ran the library statementā¦I am getting the following error
ypeError Traceback (most recent call last)
in
2 a2 = np.array([1.1, 2.1, 3.1]); b2 = np.array([1.0, 2.0, 3.0])
3 a3 = np.array([0, 1, 0]); b3 = np.array([1, 0, 0])
----> 4 print(f"squared distance between a1 and b1: {sq_dist(a1, b1):0.3f}ā)
5 print(f"squared distance between a2 and b2: {sq_dist(a2, b2):0.3f}ā)
6 print(f"squared distance between a3 and b3: {sq_dist(a3, b3):0.3f}")

TypeError: unsupported format string passed to numpy.ndarray.format

Oh, the error implies that your `sq_dist` function is returning a numpy array which is wrong. Your function should return a `float`.

Note the following formula that you donāt just have to `subtract`, `square`, but also sum over it.

Did you do the āsumā step?

Raymond

@rmwkwok

I didnt do sum stepā¦ i am not sure how to put the code hereā¦ I used tensor flow function and it didnt work either

Sudhir

@rmwkwok I running into following error
UnboundLocalError: local variable ādā referenced before assignment

Hello @Sudhir_Nandamuru, you have been using numpy functions, why donāt you use numpy function for the sum? Here is the numpy function for sum: np.sum.

Sudhir, what do you think this error means?

@rmwkwok It is variable initialization error that I missed it earlier. I got the lab working after finding an error with my code. thanks for your guidanceā¦

Sudhir

Great work Sudhir @Sudhir_Nandamuru . `sq_dist` is a small function, but it is an important success of yours.

Cheers,
Raymond

Hi @rmwkwok. In the cofi cost function if I use the np.dot function to compute dot product between x and w, doesnāt the sum you mention in earlier posts get taken care of?

Hello @David_Stulman,

It would have been better to ask a different question in a new thread, since this thread seems to be more related to the squared distance function.

I think I have not talked about anything directly related to the cofi cost function in this thread.

`np.dot` involves multiplications and additions, so you may be right.

Cheers,
Raymond