Why do I see incorrect results from the Square Root function in the Floating Point Custom Instruction 2 IP?

Description

Due to a problem in the Floating Point Custom Instruction 2 IP in the Intel® Quartus® II software versions 13.1 and later, incorrect results might be seen for Square Root operations (instruction 251, fsqrts) when the expected result is close to 1.0. 

Resolution

A patch is available to fix this problem for the Intel® Quartus® II software version 15.0.  Download and install Patch 0.12 from the following links:

• Intel Quartus II software version 15.0 Patch 0.12 for Windows (.exe)
• Intel Quartus II software 15.0 Patch 0.12 for Linux (.run)
• Readme for the Intel Quartus II software version 15.0 Patch 0.12 (.txt)

This problem is scheduled to be fixed in a future release of the Intel Quartus II software.