Analysis of the Block-Grid Method for the Solution of Laplace's Equation on Polygons with a Slit

Figure 6

The first partial derivatives 𝜕𝑈_ℎ^6(𝑀)/𝜕𝑥 and 𝜕𝑈_ℎ^6(𝑀)/𝜕𝑦 in the “singular” part for ℎ⁻¹=64, 𝑛=140.

(a)

(b)