**System Information**

Operating system and graphics card

**Blender Version**

Broken: 75381ae

Worked: (optional)

**Short description of error**

Math Result in Cycles Nodes is not correct or way not exact.

The exact same calculation done in Libre office, GeoGebra and Calculator yields in the correct Value of 1.45

Blender Result is 1.42345

Formula: IOR = (-R -2 sqrt(R)-1)/(R-1)

Libre Office Formula: =((0.0338*-1)-2 * SQRT(0.0338)-1)/(0.0338-1)

I know i do work with quite low Numbers, but since Colors are Linear in Blender and i think it is essential being able to do Math on those i do see this as a big Problem.

Or am i doing something Wrong here?

**Exact steps for others to reproduce the error**

Open Bug_MathCycles.blend

Hit Render

Check Color in Render Result

Check Math Result on your own if you like