In the forums of the Coursera course “Machine Learning” by Andrew Ng, there are many questions regarding the **dimensions** of the **input matrix** and **theta**.

Here is an intuitive guide to understanding the dimensions. Click the link below!

Understanding-Dimensions-Linear-Logistic-Regression.pdf

**In Summary: **

The dimensions of your input matrix (X) is typically clear and driven from your data.

`[ # of examples, # of input variables ]`

The dimensions of theta are driven from your input variables. In linear regression and binary classification, the number of outputs per example is typically 1:

`[ # of input variables, # of outputs per example ]`