AD5544 four quadrant application

The data sheet AD5544_AD5554.pdf Rev.H shows on page 20 how to build a four quadrant multilpying DAC by adding two operational amplifiers.

There are some issues in this part of the data sheet:

- discard the reference circuit AD588, this is the analog input of the multiplier -10V<Vin<+10V. Its explanation "Biasing the external amplifier with a 10 V offset from the reference voltage results in a full four-quadrant multiplying circuit." is nonsense.

- The formulas (3) and (4) contain no "=" and the minus in front of VREF is wrong.

I want to design a vector rotation circuit, an analog input of an I/Q signal up to 12 MHz can be phase rotated by multiplying with sin and cos of a fixed angle. I thing five AD812 together with the AD554 will do the job.