python中numpy运算出现overflow问题

Question

定义损失函数出现overflow

数据是吴恩达机器学习作业练习1中的，在计算损失函数和实现梯度下降，出现overflow，将数据都改成float64后，依然出现overflow

相关代码

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt

#加载数据
df=pd.read_csv('ex1data1-Copy1.txt',header=None,names=['population','profit'])
df.head()

population profit
0 6.1101 17.5920
1 5.5277 9.1302
2 8.5186 13.6620
3 7.0032 11.8540
4 5.8598 6.8233

df_np=df.values
df_np=np.insert(df_np,0,1.0,axis=1)

df_np.shape

X=df_np[:,0:2]
X.shape

X=X.astype(np.float64)

#将y变成列向量
y=y.reshape(97,1)
y=y.astype(np.float64)
y.shape

#定义损失函数
def cost(X,y,theta):
    inn=np.sum((np.dot(X,theta)-y)**2)
    return inn/(2*len(y))

theta=[0.0,0.0]
theta=np.array(theta,dtype='float64').reshape(2,1)

loss_theta0=cost(X,y,theta)
loss_theta0

#更新theta
def GredientDec(X,y,theta,iters,alpha):
    parameters=X.shape[1]
    loss=np.zeros((iters,1))
    
    for a in range(iters):
        error=(np.dot(X,theta)-y)
        
        for j in range(parameters):
            term=np.sum(np.multiply(error,X[:,j]))
            theta[j]=theta[j]-(alpha*term)/len(y)
            loss[a]=cost(X,y,theta)
            
    return theta,loss

np.seterr(invalid='ignore')
theta,loss=GredientDec(X,y,theta=theta,iters=1000,alpha=0.01)
theta

报错信息：<ipython-input-10-494f352e9efa>:6: RuntimeWarning: overflow encountered in square
inn=np.sum((np.dot(X,theta)-y)**2)
E:\Anaconda\lib\site-packages\numpy\core\fromnumeric.py:87: RuntimeWarning: overflow encountered in reduce
return ufunc.reduce(obj, axis, dtype, out, **passkwargs)

没有传文件的地方，只能把数据文件放在百度网盘了，麻烦了！
数据地址：
链接：https://pan.baidu.com/s/1Fp84...
提取码：r7fc
--来自百度网盘超级会员V5的分享

请问为啥出现overflow，数据都是浮点型啊，还有如何解决这一问题啊（新手入门，多多包含）