fix: arg parsing upper bound,

fix: stencil k BUG,
add: compiler performance flags

Exercise_01/src/Makefile

@@ -1,7 +1,7 @@
 
 CPP=g++
 MPICPP=mpic++
-CPPFLAGS= -std=c++17 -O3 -Wall -Wpedantic -pedantic
+CPPFLAGS= -std=c++17 -O3 -march=native -mtune=native -ffast-math -Wall -Wpedantic -pedantic
 OUT=main
 
 seriel: main.cpp Matrix.h Solver.h

Exercise_01/src/Solver.h

@@ -29,11 +29,11 @@ public:
         _nx{nx}, _ny{ny},
         _xmin{xmin}, _xmax{xmax},
         _ymin{ymin}, _ymax{ymax},
-        _stencil{ 4.0 / (h * h) + 4.0 * k * k,  /* Center */
-                 -1.0 / (h * h),                /* Bottom */
-                 -1.0 / (h * h),                /* Left */
-                 -1.0 / (h * h),                /* Up */
-                 -1.0 / (h * h)},               /* Right */
+        _stencil{ 4.0 / (h * h) + k * k,    /* Center */
+                 -1.0 / (h * h),            /* Bottom */
+                 -1.0 / (h * h),            /* Left */
+                 -1.0 / (h * h),            /* Up */
+                 -1.0 / (h * h)},           /* Right */
         _rhs(nx, ny, 0.),
         _sol(nx, ny, 0.),
         _tmp(nx, ny, 0.)

Exercise_01/src/main.cpp

@@ -80,14 +80,14 @@ int main(int argn, char* argv[]) {
         std::cerr << "error: Parsing arg 3 <iterations> failed" << std::endl;
         return -1;
     }
-    if (resolution < 10 || resolution > 65536) {
+    if (resolution < 10 || resolution > 1073741824) {
         std::cerr << "error: arg 1 <resolution> " << resolution
-            << " out of domain [10, 65536]" << std::endl;
+            << " out of domain [10, 1073741824 = 2^30]" << std::endl;
         return -1;
     }
-    if (iterations > 65536) {
+    if (iterations > 1073741824) {
         std::cerr << "error: arg 2 <iterations> " << iterations
-            << "out of domain [0, 65536]" << std::endl;
+            << "out of domain [0, 1073741824 = 2^30]" << std::endl;
         return -1;
     }