Stage 1 development: implement a new C++20 authagraph projection in the file src.projections/a60-carto- projection-authagraph.h using the same carto API as previous.

Base image for the authagraph projection is: asets/authagraph/15-SP-TESD-03-AG.pdf

From: https://narukawa-lab.jp/archives/authagraph-map/

https://www.jstage.jst.go.jp/article/jjca/60/1/60_1/_article/-char/en?novirtualissue=100253

Formula in: Formulation of AuthaGraph Map Projection and an Evaluation of its Distortion Hajime NARUKAWA Map, Journal of the Japan Cartographers Association 2022 Volume 60 Issue 1 1-16 Published: March 31, 2022 Released on J-STAGE: September 14, 2023

https://www.jstage.jst.go.jp/article/jjca/60/1/60_1/_pdf/-char/en?download=1

Stage 2 development: variable sized maps with aspect ratio constraint

Abstract any hard-coded map sizes () into variable size map sizes with the same aspect ratio.

Use the a60::carto::frame abstraction for the size of the variable projection, aka

struct area { double x, double y}; from frame.frame_area here: src.projections/a60-carto-frame.h

Stage 3 development: document implementation and usage

Index to documentation pages: index.md

Summarize the work, methods used, numeric forumlas and other relevant implementation details in docs/authagraph-implementation-notes.md

Explain and illustrate the geometric context, approach, quadrants, in docs/authagraph-context.md

Bibliography, docs/authagraph-bibliography.md