Last Updated : 28 Jun, 2025
The Floating point representation is a way to the encode numbers in a format that can handle very large and very small values. It is based on scientific notation where numbers are represented as a fraction and an exponent. In computing, this representation allows for trade-off between range and precision.
Format: A floating point number is typically represented as:
Value=Sign × Significand × BaseExponent
where:
The Floating point representation is crucial because:
The three components of floating point numbers are:
To convert the floating point into decimal, we have 3 elements in a 32-bit floating point representation:
Sign bit is the first bit of the binary representation. '1' implies negative number and '0' implies positive number. Example:
11000001110100000000000000000000
This is negative number.
Exponent is decided by the next 8 bits of binary representation. 127 is the unique number for 32 bit floating point representation. It is known as bias. It is determined by 2k-1 -1 where 'k' is the number of bits in exponent field.
There are 3 exponent bits in 8-bit representation and 8 exponent bits in 32-bit representation.
Thus
bias = 3 for 8 bit conversion (23-1 -1 = 4-1 = 3)
bias = 127 for 32 bit conversion. (28-1 -1 = 128-1 = 127)
Example:
01000001110100000000000000000000
10000011 = (131)10
131-127 = 4Hence the exponent of 2 will be 4 i.e. 24 = 16.
Mantissa is calculated from the remaining 23 bits of the binary representation. It consists of '1' and a fractional part which is determined by:
Example:
01000001110100000000000000000000
The fractional part of mantissa is given by:
1*(1/2) + 0*(1/4) + 1*(1/8) + 0*(1/16) +......... = 0.625
Thus the mantissa will be
1 + 0.625 = 1.625
The decimal number hence given as:
Decimal to Floating Point ConversionSign*Exponent*Mantissa = (-1)0*(16)*(1.625) = 26
To convert the decimal into floating point, we have 3 elements in a 32-bit floating point representation:
i) Sign (MSB)
ii) Exponent (8 bits after MSB)
iii) Mantissa (Remaining 23 bits)
Sign bit is the first bit of the binary representation. '1' implies negative number and '0' implies positive number.
Example: To convert -17 into 32-bit floating point representation Sign bit = 1
Exponent is decided by the nearest smaller or equal to 2n number. For 17, 16 is the nearest 2n. Hence the exponent of 2 will be 4 since 24 = 16. 127 is the unique number for 32 bit floating point representation. It is known as bias. It is determined by 2k-1 -1 where 'k' is the number of bits in exponent field.
Thus bias = 127 for 32 bit. (28-1 -1 = 128-1 = 127)
Now, 127 + 4 = 131
i.e. 10000011 in binary representation.
Mantissa: 17 in binary = 10001.
Move the binary point so that there is only one bit from the left. Adjust the exponent of 2 so that the value does not change. This is normalizing the number. 1.0001 x 24. Now, consider the fractional part and represented as 23 bits by adding zeros.
Advantages of Floating Point Representation00010000000000000000000
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