Update README

README.md

@@ -1,17 +1,34 @@
-# cobyla
+# cobyla - a pure Rust implementation
 
 [![tests](https://github.com/relf/cobyla/workflows/tests/badge.svg)](https://github.com/relf/cobyla/actions?query=workflow%3Atests)
 [![crates.io](https://img.shields.io/crates/v/cobyla)](https://crates.io/crates/cobyla)
 [![docs](https://docs.rs/cobyla/badge.svg)](https://docs.rs/cobyla)
 
-COBYLA an algorithm for minimizing a function of many variables. The method is derivatives free (only the function values are needed) and take into account constraints on the variables. The algorithm is described in:
+COBYLA is an algorithm for minimizing a function of many variables. The method is derivatives free (only the function values are needed) and take into account constraints on the variables. The algorithm is described in:
 
   > M.J.D. Powell, "A direct search optimization method that models the objective and constraint functions by linear interpolation," in 
   > Advances in Optimization and Numerical Analysis Mathematics and Its Applications, vol. 275 (eds. Susana Gomez and Jean-Pierre Hennart), 
   > Kluwer Academic Publishers, pp. 51-67 (1994).
 
+The algorithm comes into two flavours :
+* As an [argmin solver](), the Rust code was generated from the C code from [here](https://github.com/emmt/Algorithms/tree/master/cobyla) 
+* As a function `minimize`, the Rust code was generated from the C code the [NLopt](https://github.com/stevengj/nlopt) project (version 2.7.1)  
+
+In both cases, an initial transpilation was done with [c2rust](https://github.com/immunant/c2rust) then the code was manually edited to make it work. Note that the callback mechanism
+is inspired from the excellent Rust binding of NLopt, namely [rust-nlopt](https://github.com/adwhit/rust-nlopt)
+
 ## Example
 
 ```bash
 cargo run --example paraboloid
-```
+```
+
+## Related projects
+
+* [rust-nlopt](https://github.com/adwhit/rust-nlopt): the Rust binding of the [NLopt project](https://nlopt.readthedocs.io)
+* [argmin](https://github.com/argmin-rs/argmin): the pure-Rust optimization framework
+* [slsqp](https://github.com/relf/slsqp): As for `cobyla`, a pure Rust implementation of SLSQP transpiled and manually edited from NLopt C code. 
+
+## License
+
+The project is released under MIT License.