Jacobi rotation based EVD implementation

Posting what you want your code to do is not a bad first step. Next, I would suggest you make an attempt at writing this yourself in VHDL. When you run into problems, post your VHDL and the specific problem (or error message) you are having.

Are you trying to write your code for simulation only, or do you plan on implementing this in hardware?

To write this function in VHDL for hardware, some more information is needed. What environment would the VHDL code be running in? Designing your VHDL to fit into a specific part/dev board can alter how you code. Available clocks/plls are also something to consider. Data rates, data precision, and computational delay (pipelining) also need to factor in the design.