fix: make matrix indexing symbolic when not numeric so that summation…

… with matrices works

Tests need to be added for summation with matrices

public/dimensional_analysis.py

@@ -1123,8 +1123,8 @@ def UniversalInverse(expression: Expr) -> Expr:
 
 def IndexMatrix(expression: Expr, i: Expr, j: Expr) -> Expr:
     for subscript in cast(list[ExprWithAssumptions], (i,j)):
-        if not (subscript.is_real and subscript.is_finite and subscript.is_integer and cast(int, subscript) > 0):
-            raise Exception("Matrix indices must evaluate to a finite real integer and be greater than 0")
+        if subscript.is_real and cast(int, subscript) <= 0:
+            raise Exception("Matrix indices must be greater than 0")
 
     return expression[i-1, j-1] # type: ignore
 

src/constants.ts

@@ -6,7 +6,7 @@ export const INLINE_SHORTCUTS = {
     '~': '\\approx',
     'sqrt': '\\sqrt{#?}',
     '$int': '\\int _{#?}^{#?}\\left(#?\\right)\\mathrm{d}\\left(#?\\right)',
-    '$sum': '\\sum_{#?=#?}^{#?}\left(#?\\right)',
+    '$sum': '\\sum_{#?=#?}^{#?}\\left(#?\\right)',
     '$prime': '\\frac{\\mathrm{d}}{\\mathrm{d}\\left(#?\\right)}\\left(#?\\right)',
     '$doubleprime': '\\frac{\\mathrm{d}^{2}}{\\mathrm{d}\\left(#?\\right)^{2}}\\left(#?\\right)',
     '$tripleprime': '\\frac{\\mathrm{d}^{3}}{\\mathrm{d}\\left(#?\\right)^{3}}\\left(#?\\right)',

tests/test_matrix_indexing.spec.mjs

@@ -81,15 +81,15 @@ test('Zero index', async () => {
 
   await page.waitForSelector('text=Updating...', {state: 'detached'});
 
-  await expect(page.locator("text=Matrix indices must evaluate to a finite real integer and be greater than 0")).toBeVisible();
+  await expect(page.locator("text=Matrix indices must be greater than 0")).toBeVisible();
 });
 
 test('Negative index', async () => {
   await page.setLatex(0, String.raw`\begin{bmatrix}a & b\\ c & d\\ e & f\end{bmatrix}_{1,-1}=`);
 
   await page.waitForSelector('text=Updating...', {state: 'detached'});
 
-  await expect(page.locator("text=Matrix indices must evaluate to a finite real integer and be greater than 0")).toBeVisible();
+  await expect(page.locator("text=Matrix indices must be greater than 0")).toBeVisible();
 });
 
 test('Out of range index', async () => {
@@ -105,15 +105,16 @@ test('Noninteger index', async () => {
 
   await page.waitForSelector('text=Updating...', {state: 'detached'});
 
-  await expect(page.locator("text=Matrix indices must evaluate to a finite real integer and be greater than 0")).toBeVisible();
+  await expect(page.locator("text=IndexError, Invalid index")).toBeVisible();
 });
 
 test('Nonnumeric index', async () => {
   await page.setLatex(0, String.raw`\begin{bmatrix}a & b\\ c & d\\ e & f\end{bmatrix}_{1,z}=`);
 
   await page.waitForSelector('text=Updating...', {state: 'detached'});
 
-  await expect(page.locator("text=Matrix indices must evaluate to a finite real integer and be greater than 0")).toBeVisible();
+  let content = await page.textContent('#result-value-0');
+  expect(content).toBe(String.raw`\left[\begin{matrix}a & b\\c & d\\e & f\end{matrix}\right]_{0, z - 1}`);
 });
 
 test('Indexing with expression', async () => {