Fixed-Point Blockset

fixptbestprec

Determine the maximum precision available for the fixed-point representation of a value

Syntax

• out = fixptbestprec(RealWorldValue,TotalBits,IsSigned)
  out = fixptbestprec(RealWorldValue,FixPtDataType)
  

Description

out = fixptbestprec(RealWorldValue,TotalBits,IsSigned) determines the maximum precision for the fixed-point representation of the real-world value specified by RealWorldValue. You specify the number of bits for the fixed- point number with TotalBits, and you specify whether the fixed-point number is signed with IsSigned. If IsSigned is 1, the number is signed. If IsSigned is 0, the number is not signed. The maximum precision is returned to out.

out = fixptbestprec(RealWorldValue,FixPtDataType) determines the maximum precision based on the data type specified by FixPtDataType.

Example

The following command returns the maximum precision available for the real-world value 4/3 using a signed, 8-bit number:

• out = fixptbestprec(4/3,8,1)
  out =
     0.015625
  

Alternatively, you can specify the fixed-point data type:

• out = fixptbestprec(4/3,sfix(8))
  out =
     0.015625
  

This value means that the maximum precision available for 4/3 is obtained by placing six bits to the right of the radix point since 2^-6 equals 0.015625:

01.010101

You can use the maximum precision as the scaling parameter in fixed-point blocks.

See Also

fixptbestexp, sfix, ufix

fixptbestexp

fixpt_convert