[interpolation] make sure the value for x determined when generating the grid are within the valid range

Description

make sure the value for x determined when generating the grind for the interpolation points is within the valid range to avoid subtle issues related to the representation of float numbers.

Conformity

• Changelog entry
• Unit tests
• Update INSTALL
• Downport
• Fixes: #841 (closed)

When external dependencies are removed

• Reporting to ...