Skip import of Eigen, fix compilation

Author: julien-michot

CMakeLists.txt

@@ -7,14 +7,11 @@ project(tinyopt-example VERSION 0.0.1
 # Compiler flags
 set(CMAKE_CXX_STANDARD 20)
 
-# Import Eigen (Mandatory)
-find_package(Eigen3 REQUIRED NO_MODULE)
-
 # Find Tinyopt, fetch it if not found
 find_package(Tinyopt)
 
 if (NOT Tinyopt_FOUND)
-  message("Tinyopt not found locally, fetching it")
+  message("Tinyopt not found locally, fetching it...")
   include(FetchContent)
   FetchContent_Declare(
       tinyopt
@@ -29,4 +26,4 @@ endif()
 
 # Header-only library
 add_executable(example src/example.cpp)
-target_link_libraries(example PUBLIC Eigen3::Eigen tinyopt)
+target_link_libraries(example PUBLIC tinyopt)

README.md

@@ -7,26 +7,40 @@ Minimal Tinyopt project
 ## CMakeLists.txt
 
 ```cmake
-set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD 20) # Minimum is c++17
 
-find_package(Eigen3 REQUIRED NO_MODULE)
 find_package(Tinyopt)
 
 add_executable(example src/example.cpp)
-target_link_libraries(example PUBLIC Eigen3::Eigen tinyopt)
+target_link_libraries(example PUBLIC tinyopt)
 ```
 
+### Alternative using `git submodule`
+
+The provided CMakeLists.txt is fetching Tinyopt if it's not found locally but you can also
+install it using git submodules, e.g.
+```shell
+git submodule add https://github.com/julien-michot/tinyopt.git third_party/tinyopt
+git submodule init
+git submodule update --init --recursive
+```
+and add it to the project:
+
+```cmake
+add_subdirectory(${CMAKE_CURRENT_SOURCE_DIR}/third_party/tinyopt)
+```
 
 ## Example.cpp
 
 Here is an example of usage of 'tinyopt' where we compute the square root of 2.
 
 ```cpp
 #include <tinyopt/tinyopt.h>
+using namespace tinyopt::nlls; // Default Non-Linear Least Square Optimizer
 
 int main(int, char **argv) {
   double x = 1;
-  tinyopt::Optimize(x, [](const auto &x) { return x * x - 2.0; });
+  Optimize(x, [](const auto &x) { return x * x - 2.0; });
   std::cout << "What's √2 already?\n" << x << "\n";
   return 0;
 }