matlab stepz,Step response of discrete-time filter

Arithmetic used in the filter analysis, specified as 'double',

'single', or 'Fixed'. When the arithmetic

input is not specified and the filter System object is unlocked, the analysis tool assumes a double-precision filter. When the

arithmetic input is not specified and the System object is locked, the function performs the analysis based on the data type of

the locked input.

The 'Fixed' value applies to filter System objects with fixed-point

properties only.

When the 'Arithmetic' input argument is specified as

'Fixed' and the filter object has the data type of the

coefficients set to 'Same word length as input', the arithmetic

analysis depends on whether the System object is unlocked or locked.

unlocked –– The analysis object function cannot determine the coefficients

data type. The function assumes that the coefficients data type is signed,

has a 16-bit word length, and is auto scaled. The function performs

fixed-point analysis based on this assumption.

locked –– When the input data type is 'double' or

'single', the analysis object function cannot

determine the coefficients data type. The function assumes that the data

type of the coefficients is signed, has a 16-bit word length, and is auto

scaled. The function performs fixed-point analysis based on this

assumption.

To check if the System object is locked or unlocked, use the isLocked function.

When the arithmetic input is specified as 'Fixed' and the filter

object has the data type of the coefficients set to a custom numeric type, the object

function performs fixed-point analysis based on the custom numeric data type.