def is_strictly_increasing(f, interval=S.Reals, symbol=None):
 f = sympify(f)
 free_sym = f.free_symbols
 if (symbol is None):
  if (len(free_sym) > 1):
   raise NotImplementedError('is_strictly_increasing has not yet been implemented for all multivariate expressions')
  elif (len(free_sym) == 0):
   return False
  symbol = free_sym.pop()
 df = f.diff(symbol)
 df_pos_interval = solveset((df > 0), symbol, domain=S.Reals)
 return interval.is_subset(df_pos_interval)

def is_strictly_increasing ( f , interval = S . Reals , symbol = None ) : f = sympify ( f ) free_sym = f . free_symbols if ( symbol is None ) : if ( len ( free_sym ) > 1 ) : raise NotImplementedError ( 'is_strictly_increasing has not yet been implemented for all multivariate expressions' ) elif ( len ( free_sym ) == 0 ) : return False symbol = free_sym . pop ( ) df = f . diff ( symbol ) df_pos_interval = solveset ( ( df > 0 ) , symbol , domain = S . Reals ) return interval . is_subset ( df_pos_interval )
returns if a function is strictly increasing or not .