The all-pole direct form structure implemented by the block does not have an equivalent dfilt structure, so it is not p

[omidrostaei]

The all-pole direct form structure implemented by the block does not have an equivalent dfilt structure, so it is not possible to match fixed-point numeric results between the block and a dfilt object derived from the block. However, you can reconfigure the block to use one of the available IIR structures.

dfiltblktoobj