"""Original initialized masked division; never read an uninitialized false-mask result."""
import numpy as np
import json

def safe_divide(x,mask,out):
 if not isinstance(x,np.ndarray) or x.dtype!=np.dtype('float64') or x.ndim!=1 or not 1<=x.size<=8 or not np.all(np.isfinite(x)) or np.any(np.abs(x)>10**6) or np.any((x!=0)&(np.abs(x)<1e-6)):raise ValueError('bounded1Dfloat64 array,nonzero magnitude>=1e-6')
 if not isinstance(mask,np.ndarray) or mask.dtype!=np.dtype('bool') or mask.shape!=x.shape or np.any(mask&(x==0)):raise ValueError('same-shape boolean mask never selects zero divisor')
 if not isinstance(out,np.ndarray) or out.dtype!=np.dtype('float64') or out.shape!=x.shape or not np.all(np.isfinite(out)) or np.shares_memory(out,x):raise ValueError('initialized separate float64 output of same shape')
 before=out.copy()
 with np.errstate(divide='raise',invalid='raise',over='raise'):np.divide(1.0,x,out=out,where=mask)
 oracle=np.array([1.0/float(v) if bool(flag) else float(old) for v,flag,old in zip(x,mask,before)])
 assert np.array_equal(out,oracle);assert np.array_equal(out[~mask],before[~mask]);return out.tolist()

def demo():
 x=np.array([-2.,0.,4.]);failure=None
 try:
  with np.errstate(divide='raise',invalid='raise'):np.where(x!=0,1/x,-999.)
 except FloatingPointError as err:failure=type(err).__name__
 assert failure=='FloatingPointError';mask=x!=0;out=np.full(x.shape,-999.,dtype=np.float64);main=safe_divide(x,mask,out);assert main==[-.5,-999.,.25]
 eager=[]
 def tag(name,value):eager.append(name);return value
 chosen=np.where(tag('condition',np.array([False,False,False])),tag('x_branch',np.array([1.,2.,3.])),tag('y_branch',-999.));assert eager==['condition','x_branch','y_branch'] and chosen.tolist()==[-999.]*3
 cases=[]
 for values,flags in [([1.,2.,4.],[True,True,True]),([0.,0.,0.],[False,False,False]),([-2.,0.,4.],[True,False,True]),([-1.,-4.],[False,True])]:
  aa=np.array(values,dtype=np.float64);mm=np.array(flags,dtype=bool);oo=np.full(aa.shape,-999.,dtype=np.float64);cases.append({'input':values,'mask':flags,'output':safe_divide(aa,mm,oo)})
 rejected=[]
 for label,fn in [('wrong_out_shape',lambda:safe_divide(x,mask,np.full(2,-999.))),('wrong_out_dtype',lambda:safe_divide(x,mask,np.full(3,-999,dtype=int))),('nonfinite_input',lambda:safe_divide(np.array([np.nan]),np.array([False]),np.array([-999.]))),('zero_selected',lambda:safe_divide(x,np.array([True,True,True]),np.full(3,-999.))),('mask_not_boolean',lambda:safe_divide(x,np.array([1,0,1]),np.full(3,-999.))),('input_output_alias',lambda:safe_divide(x,mask,x)),('over_budget',lambda:safe_divide(np.ones(9),np.ones(9,dtype=bool),np.zeros(9)))]:
  try:fn()
  except ValueError:rejected.append(label)
  else:raise AssertionError('expected rejection')
 return {'authored_input':x.tolist(),'unsafe_where_error':failure,'initialized_sentinel':-999.0,'mask':mask.tolist(),'safe_output':main,'all_false_where_argument_evaluation_trace':eager,'all_false_where_result':chosen.tolist(),'actual_safe_cases':cases,'invalid_cases_rejected':rejected,'numpy_version':np.__version__,'scope':'original bounded finite initialized-output NumPy demonstration, no read/assertion about uninitialized out=None cells. np.where is eager because Python evaluates call arguments, ufunc where controls writes; sentinel is declared missing marker not zero or actual observed result. No model/SDK/Opera claim'}
if __name__=='__main__':print(json.dumps(demo(),ensure_ascii=True,indent=2))