From db85c0f82fc0ebdae197c74012e2b409b4f3ec59 Mon Sep 17 00:00:00 2001
From: David Tschumperle <David.Tschumperle@unicaen.fr>
Date: Wed, 11 Sep 2024 13:37:56 +0200
Subject: [PATCH] Implementation of native softmax operator.

---
 CImg.h | 32 +++++++++++++++++++++++++++++---
 1 file changed, 29 insertions(+), 3 deletions(-)

diff --git a/CImg.h b/CImg.h
index dbcbdc0f..6e17b9fd 100644
--- a/CImg.h
+++ b/CImg.h
@@ -22379,6 +22379,19 @@ namespace cimg_library {
               _cimg_mp_const_scalar(is_scalar(arg1)?0:size(arg1));
             }
 
+            if (!std::strncmp(ss,"softmax(",8)) { // Softmax
+              _cimg_mp_op("Function 'softmax()'");
+              s1 = ss8; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
+              arg1 = compile(ss8,s1,depth1,0,block_flags);
+              arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):1;
+              _cimg_mp_check_type(arg2,2,1,0);
+              p1 = size(arg1);
+              if (p1>0) pos = is_comp_vector(arg1)?arg1:((return_comp = true), vector(p1));
+              else _cimg_mp_return(1);
+              CImg<ulongT>::vector((ulongT)mp_vector_softmax,pos,arg1,p1,arg2).move_to(code);
+              _cimg_mp_return(pos);
+            }
+
             if (!std::strncmp(ss,"solve(",6)) { // Solve square linear system
               _cimg_mp_op("Function 'solve()'");
               s1 = ss6; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
@@ -22798,7 +22811,7 @@ namespace cimg_library {
               s1 = s0; while (s1<se1 && (*s1!=',' || level[s1 - expr._data]!=clevel1)) ++s1;
               arg1 = compile(s0,s1,depth1,0,block_flags);
               arg2 = s1<se1?compile(++s1,se1,depth1,0,block_flags):2;
-              _cimg_mp_check_type(arg2,0,1,0);
+              _cimg_mp_check_type(arg2,2,1,0);
               p1 = size(arg1);
               if (p1>0) pos = is_comp_vector(arg1)?arg1:((return_comp = true), vector(p1));
               else {
@@ -29241,6 +29254,19 @@ namespace cimg_library {
         return _mp_arg(1);
       }
 
+      static double mp_vector_softmax(_cimg_math_parser& mp) {
+        const unsigned int siz = (unsigned int)mp.opcode[3];
+        const double temperature = _mp_arg(4);
+        if (siz>0) { // Vector-valued argument
+          double *const ptrd = &_mp_arg(1) + 1;
+          const double *const ptrs = &_mp_arg(2) + 1;
+          CImg<doubleT>(ptrd,siz,1,1,1,true) = CImg<doubleT>(ptrs,siz,1,1,1,true).get_softmax(temperature);
+          return cimg::type<double>::nan();
+        }
+        // Scalar-valued argument.
+        return 1;
+      }
+
       static double mp_vector_unitnorm(_cimg_math_parser& mp) {
         const unsigned int siz = (unsigned int)mp.opcode[3];
         const double p = _mp_arg(4);
@@ -30222,8 +30248,8 @@ namespace cimg_library {
       CImg<Tfloat> res(_width,_height,_depth,_spectrum);
       const T val_max = max();
       Tfloat sum = 0;
-      cimg_pragma_openmp(parallel reduction(+:sum)) {
-        cimg_pragma_openmp(for cimg_openmp_if_size(size(),4096))
+      cimg_pragma_openmp(parallel reduction(+:sum) cimg_openmp_if_size(size(),4096)) {
+        cimg_pragma_openmp(for)
         cimg_rofoff(*this,off) {
           const Tfloat val = std::exp(((Tfloat)_data[off] - val_max)/temperature);
           res[off] = val;