ABSTRACT
The most general first-order linear PDE in two independent variables x and t has the form () a u x + b u t = c u + d https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429115950/60d16bce-0919-42a4-8d50-5c0e3803c9ff/content/eq1.tif"/>
