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The following examples show how to create fixed-point data using the Fixed-Point Designer™ fi object.
Create a fixed-point number with default properties
Calling fi on a number produces a fixed-point number with default signedness and default word and fraction lengths.
fi(pi)
ans = 3.1416 DataTypeMode: Fixed-point: binary point scaling Signedness: Signed WordLength: 16 FractionLength: 13
Create a fixed-point number with specified signedness, word length, and fraction length
You can specify the signedness (1 for signed, 0 for unsigned) and the word and fraction lengths.
fi(pi,1,15,12)
ans = 3.1416 DataTypeMode: Fixed-point: binary point scaling Signedness: Signed WordLength: 15 FractionLength: 12
Create fixed-point integer values
To create fixed-point integer values, you specify a fraction length of 0.
fi (1:25,0,8,0)
ans = Columns 1 through 13 1 2 3 4 5 6 7 8 9 10 11 12 13 Columns 14 through 25 14 15 16 17 18 19 20 21 22 23 24 25 DataTypeMode: Fixed-point: binary point scaling Signedness: Unsigned WordLength: 8 FractionLength: 0
Create an array of random fixed-point values
fi(rand(4),0,12,8)
ans = 0.1484 0.8125 0.1953 0.3516 0.2578 0.2422 0.2500 0.8320 0.8398 0.9297 0.6172 0.5859 0.2539 0.3516 0.4727 0.5508 DataTypeMode: Fixed-point: binary point scaling Signedness: Unsigned WordLength: 12 FractionLength: 8
Create an array of zeros
When writing code, you sometimes want to test different data types for your variables. Separating the data types of your variables from your algorithm makes testing much simpler. By creating a table of data type definitions, you can programmatically toggle your function between floating point and fixed point data types. The following example shows how to use this technique and create an array of zeros.
T.z = fi([],1,16,0);
z = zeros(2,3,'like',T.z)
z = 0 0 0 0 0 0 DataTypeMode: Fixed-point: binary point scaling Signedness: Signed WordLength: 16 FractionLength: 0
Note: For a full example showing this technique's implementation, see Implement FIR Filter Algorithm for Floating-Point and Fixed-Point Types using cast and zeros. |