# Errata

This is the errata page for the *Projective Geometric Algebra Illuminated*. To find out which printing you have, look on the copyright page. If you believe you have found an error that should be added to this list, please email the author (lengyel@terathon.com).

## Third Printing and Earlier

**Page 70.**In the line following Equation (2.71), the product of the bulks should use the antiwedge product and appear as $$\mathbf a_\unicode["segoe ui symbol"]{x25CF} \vee \mathbf b_\unicode["segoe ui symbol"]{x25CF}$$.

## Second Printing and Earlier

**Page 248.**In Equation (5.27), the operator $$\mathbf D$$ should be dualized as $$\mathbf D^\unicode["segoe ui symbol"]{x2605}$$. It should also be dualized in the first factor of the sandwich product in the sentence that follows this equation.

## First Printing

**Page 84.**In Table 2.16, both bulk duals of $$\mathbf e_4$$ should be 0. The table should look like the one on the wiki page for duals.

**Page 156.**The number of multiply-adds required for transforming a line with a motor did not include the work needed to calculate $$\mathbf a$$, $$\mathbf b$$, and $$\mathbf c$$. Each cross product adds 6 multiply-adds, so the correct total for transforming a line is 54.

**Page 156.**Similarly, the number of multiply-adds required for transforming a plane with a motor did not include the work needed to calculate $$\mathbf a$$. The correct total for transforming a plane is 35.