unsupported operand types for * : 'float' and 'decimal'

Question

for a in range(0,size):
    et = 0.0023*ralist[rows[a][2]] * ( 0.5*(rows[a][3] + rows[a][4])  + 17.8 ) * ( rows[a][3] - rows[a][4])**(0.5)
    eto_values.insert(a,et)

When I try to run the code, I get the following error:

unsupported operand types for * : 'float' and  'decimal'

I have tried using decimal.Decimal() function also. Can someone please tell me how to clear this error?

Solution 1

You cant multiply or devise float and decimal.Decimal() types, what I would suggest is multiplying by Decimal('0.0023') and Decimal('0.5'):

for a in range(0,size)
  et = Decimal('0.0023')*ralist[rows[a][2]] * ( Decimal('0.5')*(rows[a][3] + rows[a][4]) + 17.8 ) * ( rows[a][3] - rows[a][4])**(0.5)
  eto_values.insert(a,et)

Solution 2

>>> from decimal import *
>>> Decimal(1.2) * Decimal(3.4)
Decimal('4.079999999999999742428258287')
>>> Decimal(1.2) * 3.4
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for *: 'decimal.Decimal' and 'float'

Comments

[user2357112]

"Decimal(0.0023) and Decimal(0.5)" - no! If you're going to hardcode a Decimal into your source, always construct it from a string, like Decimal('0.0023'), to avoid having the value rounded to what can be represented in a float.

[endolith]

devise → divide?