added scaling fix

Author: matthew-hennefarth

source/matplot/axes_objects/vectors.cpp

@@ -117,12 +117,12 @@ namespace matplot {
                 }
 
                 if (normalize_ && m_value != 0) {
-                    double length = sqrt(u_value * u_value + v_value * v_value +
+                    double mag = sqrt(u_value * u_value + v_value * v_value +
                                          w_value * w_value);
-                    double scale = length / m_value;
-                    u_value *= scale / length;
-                    v_value *= scale / length;
-                    w_value *= scale / length;
+                    double scale = mag / m_value;
+                    u_value *= scale / mag;
+                    v_value *= scale / mag;
+                    w_value *= scale / mag;
                 }
 
                 ss << "  " << u_value;
@@ -432,4 +432,12 @@ namespace matplot {
         return *this;
     }
 
+    double vectors::scale() const { return scale_; }
+    
+    class vectors &vectors::scale(double scale) {
+      scale_ = scale;
+      touch();
+      return *this;
+    }
+
 } // namespace matplot

source/matplot/axes_objects/vectors.h

@@ -115,6 +115,9 @@ namespace matplot {
         bool normalize() const;
         class vectors &normalize(bool normalize);
 
+        double scale() const;
+        class vectors &scale(double scale);
+
       public /* getters and setters bypassing the line_spec */:
         float line_width() const;
         class vectors &line_width(float line_width);
@@ -214,6 +217,9 @@ namespace matplot {
         std::vector<float> marker_sizes_{};
         std::vector<double> marker_colors_{};
 
+        /// Scale of vectors
+        double scale_{1};
+
         /// Draw line as impulse
         bool impulse_{false};
 

source/matplot/core/axes_type.cpp

@@ -4631,14 +4631,14 @@ namespace matplot {
                       w, [&](double w) { return (w / w_max) * scale * z_max; })
                 : w;
         std::vector<double> m;
-        m.reserve(u.size());
         for (int i = 0; i < u.size(); i++) {
-            double mag = sqrt(u[i] * u[i] + v[i] * v[i] + w[i] * w[i]);
+            double mag = sqrt((u[i] * u[i]) + (v[i] * v[i]) + (w[i] * w[i]));
             m.emplace_back(mag);
         }
 
         vectors_handle l = std::make_shared<class vectors>(
             this, x, y, z, u_scaled, v_scaled, w_scaled, m, line_spec);
+        l->scale(scale);
         this->emplace_object(l);
 
         return l;