variable nearest_node_threshold

Author: gtheler

src/feenox.h

@@ -1665,6 +1665,8 @@ struct feenox_t {
     var_t *on_gsl_error;
     var_t *on_ida_error;
 //    var_t *realtime_scale;
+    
+    var_t *nearest_node_threshold;
   } special_vars;
 
 

src/flow/init.c

@@ -469,6 +469,16 @@ int feenox_init_special_objects(void) {
 //va+realtime_scale+detail and execution will proceed as quick as possible with no delays.
 //  feenox_special_var(realtime_scale) = feenox_get_or_define_variable_get_ptr("realtime_scale");
 
+///va+nearest_node_threshold+desc Threshold distance to interpolate instead of using the nearest-node value.
+///va+nearest_node_threshold+detail When evaluating a multi-dimensional point-defined function $F(\vec{x})$, if $\vec{x}$ is
+///va+nearest_node_threshold+detail “close enough” to one of the definition points, the value of the defined point is returned.
+///va+nearest_node_threshold+detail Otherwise, FeenoX will interpolate the definition points---depending on the settings on how $F(\vec{x})$ was defined.
+///va+nearest_node_threshold+detail This variable controls what “close enough” means as an euclidean distance.
+///va+nearest_node_threshold+detail The default value $\left(\frac{1}{2}\right)^20 \appox 10^{-8}$.
+  feenox_special_var(nearest_node_threshold) = feenox_get_or_define_variable_get_ptr("nearest_node_threshold");
+  feenox_special_var_value(nearest_node_threshold) = DEFAULT_MULTIDIM_INTERPOLATION_THRESHOLD;
+  
+  
   // standard unix files 
   feenox_call(feenox_define_file("stdin", "stdin", 0, "r"));
   feenox.special_files._stdin = feenox_get_file_ptr("stdin");

src/math/function.c

@@ -265,7 +265,7 @@ int feenox_function_init(function_t *this) {
 
   if (this->algebraic_expression.items == NULL) {
 
-    this->multidim_threshold = (this->expr_multidim_threshold.items != NULL) ? feenox_expression_eval(&this->expr_multidim_threshold) : DEFAULT_MULTIDIM_INTERPOLATION_THRESHOLD;
+    this->multidim_threshold = (this->expr_multidim_threshold.items != NULL) ? feenox_expression_eval(&this->expr_multidim_threshold) : feenox_special_var_value(nearest_node_threshold);
 
     if (this->vector_argument != NULL) {
       for (unsigned int i = 0; i < this->n_arguments; i++) {

src/parser/parser.c

@@ -1276,7 +1276,7 @@ int feenox_parse_function(void) {
 ///kw+FUNCTION+detail @
 ///kw+FUNCTION+usage [ INTERPOLATION_THRESHOLD <expr> ]
 ///kw+FUNCTION+detail For $n>1$, if the euclidean distance between the arguments and the definition points is smaller than `INTERPOLATION_THRESHOLD`, the definition point is returned and no interpolation is performed.
-///kw+FUNCTION+detail Default value is square root of `DEFAULT_MULTIDIM_INTERPOLATION_THRESHOLD`.
+///kw+FUNCTION+detail Otherwise, the value of the special variable `nearest_node_threshold` at the moment the function is defined is used as the threshold.
       } else if (strcasecmp(token, "INTERPOLATION_THRESHOLD") == 0) {
 
        feenox_parser_expression(&function->expr_multidim_threshold);