Changed matrix indexes of expression parser to one-based (Fixed #66)

HISTORY.md

@@ -2,6 +2,13 @@
 https://github.com/josdejong/mathjs
 
 
+## 2013-08-22, version 0.13.0
+
+- Changed matrix indexes of the expression parser to one-based with the
+  upper-bound included, similar to most math applications. Note that on a
+  JavaScript level, math.js uses zero-based indexes with excluded upper-bound.
+
+
 ## 2013-08-22, version 0.12.1
 
 - Fixed outdated version of README.md.

README.md

@@ -419,18 +419,21 @@ var c = math.multiply(a, b);                    // Matrix, [[19, 22], [43, 50]]
 var d = c.get(math.index(1, 0));                // 43
 ```
 
-Matrices are supported by the parser:
+Matrices are supported by the parser. *IMPORTANT:* matrix indexes and ranges work
+different from the indexes in JavaScript: They are one-based with an included
+upper-bound, similar to most math applications.
+
 
 ```js
 parser = math.parser();
 
 parser.eval('a = [1, 2; 3, 4]');                // Matrix, [[1, 2], [3, 4]]
 parser.eval('b = zeros(2, 2)');                 // Matrix, [[0, 0], [0, 0]]
-parser.eval('b[0, 0:2] = [5, 6]');              // Matrix, [[5, 6], [0, 0]]
-parser.eval('b[1, :] = [7, 8]');                // Matrix, [[5, 6], [7, 8]]
+parser.eval('b(1, 1:2) = [5, 6]');              // Matrix, [[5, 6], [0, 0]]
+parser.eval('b(2, :) = [7, 8]');                // Matrix, [[5, 6], [7, 8]]
 parser.eval('c = a * b');                       // Matrix, [[19, 22], [43, 50]]
-parser.eval('d = c[1, 0]');                     // 43
-parser.eval('e = c[1, 0:end]');                 // Matrix, [[43, 50]]
+parser.eval('d = c(2, 1)');                     // 43
+parser.eval('e = c(2, 1:end)');                 // Matrix, [[43, 50]]
 ```
 
 

examples/expressions.js

@@ -128,6 +128,19 @@ print(parser.eval('x + 3'));                    // 6.5
 print(parser.eval('function f(x, y) = x^y'));   // f(x, y)
 print(parser.eval('f(2, 3)'));                  // 8
 
+// manipulate matrices
+// Note that matrix indexes in the expression parser are one-based with the
+// upper-bound included. On a JavaScript level however, math.js uses zero-based
+// indexes with an excluded upper-bound.
+console.log('\nmanipulate matrices');
+print(parser.eval('k = [1, 2; 3, 4]'));         // [[1, 2], [3, 4]]
+print(parser.eval('l = zeros(2, 2)'));          // [[0, 0], [0, 0]]
+print(parser.eval('l(1, 1:2) = [5, 6]'));       // [[5, 6], [0, 0]]
+print(parser.eval('l(2, :) = [7, 8]'));         // [[5, 6], [7, 8]]
+print(parser.eval('m = k * l'));                // [[19, 22], [43, 50]]
+print(parser.eval('n = m(2, 1)'));              // 43
+print(parser.eval('n = m(:, 1)'));              // [[19], [43]]
+
 // get and set variables and functions
 console.log('\nget and set variables and function in the scope of the parser');
 var x = parser.get('x');                        // x = 7

examples/matrices.js

@@ -82,14 +82,3 @@ print(math.range(0, 18, 3));                // [0, 3, 6, 9, 12, 15]
 print(math.range('2:-1:-3'));               // [2, 1, 0, -1, -2]
 print(math.factorial(math.range('1:6')));   // [1, 2, 6, 24, 120]
 console.log();
-
-console.log('use the expression parser');
-var parser = math.parser();
-print(parser.eval('d = [1, 2; 3, 4]'));     // [[1, 2], [3, 4]]
-print(parser.eval('e = zeros(2, 2)'));      // [[0, 0], [0, 0]]
-print(parser.eval('e[0, 0:2] = [5, 6]'));   // [[5, 6], [0, 0]]
-print(parser.eval('e[1, :] = [7, 8]'));     // [[5, 6], [7, 8]]
-print(parser.eval('f = d * e'));            // [[19, 22], [43, 50]]
-print(parser.eval('g = f[1, 0]'));          // 43
-print(parser.eval('g = f[:, 0]'));          // [[19], [43]]
-console.log();

lib/docs/function/matrix/diag.js

@@ -7,8 +7,8 @@ module.exports = {
   ],
   'description': 'Create a diagonal matrix or retrieve the diagonal of a matrix. When x is a vector, a matrix with the vector values on the diagonal will be returned. When x is a matrix, a vector with the diagonal values of the matrix is returned.When k is provided, the k-th diagonal will be filled in or retrieved, if k is positive, the values are placed on the super diagonal. When k is negative, the values are placed on the sub diagonal.',
   'examples': [
-    'diag(1:4)',
-    'diag(1:4, 1)',
+    'diag(1:3)',
+    'diag(1:3, 1)',
     'a = [1, 2, 3; 4, 5, 6; 7, 8, 9]',
     'diag(a)'
   ],

lib/docs/function/matrix/range.js

@@ -12,12 +12,12 @@ module.exports = {
       'Create a range. Lower bound of the range is included, upper bound is excluded.',
   'examples': [
     '1:5',
-    '3:-1:-4',
+    '3:-1:-3',
     'range(3, 7)',
     'range(0, 12, 2)',
-    'range("4:11")',
-    'a = [0, 1, 2, 3; 4, 5, 6]',
-    'a(1:2)'
+    'range("4:10")',
+    'a = [1, 2, 3, 4; 5, 6, 7, 8]',
+    'a(1:2, 1:2)'
   ],
   'seealso': [
     'concat', 'det', 'diag', 'eye', 'inv', 'ones', 'size', 'squeeze', 'subset', 'transpose', 'zeros'

lib/docs/function/matrix/subset.js

@@ -13,11 +13,11 @@ module.exports = {
   'examples': [
     'd = [1, 2; 3, 4]',
     'e = []',
-    'e[0, 0:2] = [5, 6]',
-    'e[1, :] = [7, 8]',
+    'e(1, 1:2) = [5, 6]',
+    'e(2, :) = [7, 8]',
     'f = d * e',
-    'f[1, 0]',
-    'f[:, 0]'
+    'f(2, 1)',
+    'f(:, 1)'
   ],
   'seealso': [
     'concat', 'det', 'diag', 'eye', 'inv', 'ones', 'range', 'size', 'squeeze', 'transpose', 'zeros'

lib/expr/node/ParamsNode.js

@@ -87,7 +87,39 @@ ParamsNode.prototype.eval = function() {
     return obj.apply(this, results);
   }
   else {
-    throw new TypeError('Function expected');
+    // evaluate the parameters as index
+    params = this.params;
+    results = [];
+    for (i = 0, len = this.params.length; i < len; i++) {
+      var param = params[i];
+      var result;
+
+      if (param instanceof RangeNode) {
+        result = param.toRange();
+      }
+      else {
+        result = param.eval();
+      }
+
+      // change from one-based to zero-based range
+      if (result instanceof Range) {
+        result.start --;
+        result.end --;
+      }
+      else if (isNumber(result)) {
+        // number
+        result--;
+      }
+      else {
+        throw new TypeError('Number or Range expected');
+      }
+
+      results[i] = result;
+    }
+
+    // get a subset of the object
+    var index = Index.create(results);
+    return this.math.subset(obj, index);
   }
 };