normalize line segment arg order when compare

Author: dqnykamp

build/math-expressions.js

@@ -25,13 +25,13 @@ const equals = function (expr, other, {
   let exprNormalized = expr.evaluate_numbers({ max_digits: Infinity })
     .normalize_function_names()
     .normalize_applied_functions()
-    .normalize_angle_arg_order()
+    .normalize_angle_linesegment_arg_order()
     .remove_scaling_units()
     .simplify();
   let otherNormalized = other.evaluate_numbers({ max_digits: Infinity })
     .normalize_function_names()
     .normalize_applied_functions()
-    .normalize_angle_arg_order()
+    .normalize_angle_linesegment_arg_order()
     .remove_scaling_units()
     .simplify();
 

build/math-expressions_umd.js

@@ -14,11 +14,11 @@ export const equals = function (expr, other, {
   let exprNormalized = expr
     .normalize_function_names()
     .normalize_applied_functions()
-    .normalize_angle_arg_order();
+    .normalize_angle_linesegment_arg_order();
   let otherNormalized = other
     .normalize_function_names()
     .normalize_applied_functions()
-    .normalize_angle_arg_order();
+    .normalize_angle_linesegment_arg_order();
 
   return tree_equal(exprNormalized.tree, otherNormalized.tree, {
     allowed_error_in_numbers: allowed_error_in_numbers,

lib/expression/equality.js

@@ -223,7 +223,7 @@ function constants_to_floats(expr_or_tree) {
 
 }
 
-function normalize_angle_arg_order(expr_or_tree) {
+function normalize_angle_linesegment_arg_order(expr_or_tree) {
   var tree = get_tree(expr_or_tree);
 
   if (!Array.isArray(tree)) {
@@ -237,11 +237,17 @@ function normalize_angle_arg_order(expr_or_tree) {
     operands.reverse();
     return [operator, ...operands];
   }
+
+  if(operator === "linesegment" && operands.length === 2 && compare_function(operands[0], operands[1]) === 1) {
+    operands.reverse();
+    return [operator, ...operands];
+  }
+
   return tree;
 }
 
 export {
   normalize_function_names, normalize_applied_functions, log_subscript_to_two_arg_log,
   substitute_abs, default_order, constants_to_floats,
-  normalize_angle_arg_order
+  normalize_angle_linesegment_arg_order
 };

lib/expression/equality/syntax.js

@@ -1,7 +1,7 @@
 {
   "name": "math-expressions",
   "description": "Perform basic equality testing and symbolic computations on mathematical expressions involving transcendental functions",
-  "version": "2.0.0-alpha57",
+  "version": "2.0.0-alpha58",
   "author": {
     "name": "Jim Fowler",
     "email": "[email protected]",

lib/expression/normalization/standard_form.js

@@ -376,6 +376,7 @@ describe("expression", function () {
     ['x++--y', 'x+y'],
     ['x--y', 'x+y'],
     ['∠ABC', '∠CBA'],
+    ['linesegment(A,B)', 'linesegment(B,A)'],
     ['$5', '$3+$2'],
     ['$5', '$9-$4'],
     ['$xy+a$b', '$(xy+ab)'],
@@ -487,6 +488,7 @@ describe("expression", function () {
     ['log^2(x)', 'log(x)^2'],
     ['ln^2(x)', 'ln(x)^2'],
     ['∠ABC', '∠ACB'],
+    ['linesegment(A,B)', 'linesegment(A,C)'],
     ['$5', '5'],
     ['$x', 'x'],
     ['∫_a^b xdx', '∫_(2a)^b xdx'],
@@ -635,6 +637,7 @@ describe("expression", function () {
     ["f'''(x)", "f(x)'''"],
     ['x+-y', 'x-y'],
     ['∠ABC', '∠CBA'],
+    ['linesegment(A,B)', 'linesegment(B,A)'],
   ];
 
   _.each(symbolic_equivalences, function (equiv) {
@@ -839,6 +842,7 @@ describe("expression", function () {
     ['x++--y', 'x+y'],
     ['x--y', 'x+y'],
     ['∠ABC', '∠ACB'],
+    ['linesegment(A,B)', 'linesegment(A,C)'],
     ['50%', '1/2'],
     ['180 deg', 'pi'],
     ['x ∈ A', 'A ∋ x'],