Learn more about Filter Design Toolbox

Data Types

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Data Type Support Fixed Data Type Support Single Data Type Support

Data Type Support

There are three different data types supported in Filter Design Toolbox software:

• Fixed — Requires Fixed Point Toolbox and is supported by packages listed in Fixed Data Type Support.

• Double — Double precision, floating point and is the default data type for Filter Design Toolbox software; accepted by all functions

• Single — Single precision, floating point and is supported by specific packages outlined in Single Data Type Support.

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Fixed Data Type Support

To use fixed data type, you must have Fixed Point Toolbox. Type ver at the MATLAB command prompt to get a listing of all installed products.

The fixed data type is reserved for any filter whose property arithmetic is set to fixed. Furthermore all functions that work with this filter, whether in analysis or design, also accept and support the fixed data types.

To set the filter's arithmetic property:

>> f = fdesign.bandpass(.35,.45,.55,.65,60,1,60);
>> Hf = design(f, 'equiripple');
>> Hf.Arithmetic = 'fixed';

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Single Data Type Support

The support of the single data types comes in two varieties. First, input data of type single can be fed into a double filter, where it is immediately converted to double. Thus, while the filter still operates in the double mode, the single data type input does not break it. The second variety is where the filter itself is set to single precision. In this case, it accepts only single data type input, performs all calculations, and outputs data in single precision. Furthermore, such analyses as noisepsd and freqrespest also operate in single precision.

To set the filter to single precision:

>> f = fdesign.bandpass(.35,.45,.55,.65,60,1,60);
>> Hf = design(f, 'equiripple');
>> Hf.Arithmetic = 'single';

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Floating-Point to Fixed-Point Conversion

Designing Adaptive Filters

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