Transfer Fcn Direct Form II Time Varying

Implement time varying Direct Form II realization of transfer function


Additional Math & Discrete / Additional Discrete


The Transfer Fcn Direct Form II Time Varying block implements a Direct Form II realization of the specified transfer function. The block supports only single input-single output (SISO) transfer functions.

The input signal labeled Den No Lead contains the denominator coefficients of the transfer function. The full denominator has a leading coefficient of one, but it is excluded from the input signal. For example, a denominator of [1 -1.7 0.72] is represented by a signal with the value [-1.7 0.72]. The input signal labeled Num contains the numerator coefficients. The data types of the numerator and denominator coefficients can be different, but the length of the numerator vector and the full denominator vector must be the same. Pad the numerator vector with zeros, if needed.

The block automatically selects the data types and scalings of the output, the coefficients, and any temporary variables.

Data Type Support

The Transfer Fcn Direct Form II Time Varying block accepts signals of the following data types:

  • Floating point

  • Built-in integer

  • Fixed point

For more information, see Data Types Supported by Simulink in the Simulink® documentation.


Initial condition

Set the initial condition.

Integer rounding mode

Specify the rounding mode for fixed-point operations. For more information, see Rounding (Fixed-Point Designer). in the Fixed-Point Designer™ documentation.

Saturate to max or min when overflows occur

Select to have overflows saturate to the maximum or minimum value that the data type can represent. Otherwise, overflows wrap.

When you select this check box, saturation applies to every internal operation on the block, not just the output or result. In general, the code generation process can detect when overflow is not possible. In this case, the code generator does not produce saturation code.


Data Types

Double | Single | Boolean | Base Integer | Fixed-Point

Direct Feedthrough


Multidimensional Signals


Variable-Size Signals


Zero-Crossing Detection


Code Generation


Introduced before R2006a

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