Category Archives: Math

Matrix Cycle in 3D

Update 02/23: here is better picture:


Linear transformation in 3D graphics can be tricky, here is as “Matrix Cycle” that should help to better understand transition between spaces. The tricky part is actual numerical representation (or direction) in the transformation matrix.   Some info about  also here (nice notation of actual numerical matrix direction) nice online demo here 

following picture is from :


other references:

from Model to Screen:



transformation in AR

Geometric proof of vector dot product

dotProof Source: colorful introduction to Linear Algebra (may 2014) Cosine Similarity – understanding it as volume of parallelepiped cosineSimilarity Another good source for understanding dot product : dot_product_components dot_product_rotation

other resources:

Significance &Application of Cross product and Dot product.

Independence of  Perpendicular components of the motion

Math Insight:

\frac{a\cdot b}{\left \| a\right \|}= cos\alpha \left \| b \right \|

“projection” of vector b on a equals cosine of angle between them times the length of b or vice versa projection of a on b:


Dot product Identities, some pictures taken from