Added isEye and isZero to the Linear Algebra module. (#22695)

Relevant issue:
#22682
It was pointed out that we should have `isZero` and `isEye` methods in
the Linear Algebra module. This PR adds these.
Added two `isEye` and `isZero` to the linear algebra module. 

- [ ] Paratest
[reviewed by @jeremiah-corrado]

modules/packages/LinearAlgebra.chpl

@@ -1450,6 +1450,42 @@ private proc _isDiag(A: [?D] ?eltType) {
   return true;
 }
 
+/* Return `true` if matrix is the additive identity (zero matrix). */
+proc isZero(A: [?D] ?eltType) where isDenseMatrix(A) {
+  return _isZero(A);
+}
+
+private proc _isZero(A: [?D] ?eltType) {
+  if D.rank != 2 then
+    compilerError("Rank is not 2");
+
+  for (i, j) in D {
+    if A[i, j] != 0 then return false;
+  }
+  return true;
+}
+
+private proc _isEye(A: [?D] ?eltType) {
+  if D.rank != 2 then
+    compilerError("Rank is not 2");
+
+  if !isSquare(A) then return false;
+
+  for (i, j) in D {
+    if i == j {
+      if A[i, j] != 1 then return false;
+    } else {
+      if A[i, j] != 0 then return false;
+    }
+  }
+
+  return true;
+}
+
+/* Return `true` if matrix is the multiplicative identity (identity matrix).  */
+proc isEye(A: [?D] ?eltType) where isDenseMatrix(A) {
+  return _isEye(A);
+}
 
 /* Return `true` if matrix is Hermitian */
 proc isHermitian(A: [?D]) where isDenseMatrix(A) {
@@ -3400,6 +3436,15 @@ module Sparse {
     return _isDiag(A);
   }
 
+  /* Return `true` if sparse matrix is the additive identity (zero matrix). */
+  proc isZero(A: [?D] ?eltType) where A.isSparse() {
+    return _isZero(A);
+  }
+
+  /* Return `true` if sparse matrix is the multiplicative identity (identity matrix).  */
+  proc isEye(A: [?D] ?eltType) where A.isSparse() {
+    return _isEye(A);
+  }
 
   /* Return ``true`` if matrix is Hermitian. Supports CSR and COO arrays. */
   proc isHermitian(A: [?D]) where A.isSparse() {

test/library/packages/LinearAlgebra/correctness/testIdentity.chpl

@@ -0,0 +1,10 @@
+use LinearAlgebra;
+
+
+config const n = 100;
+
+var A = eye(n);
+writeln(isEye(A));
+
+var B = Matrix([0,0,0], [0,0,0], eltType=real);
+writeln(isEye(B));

test/library/packages/LinearAlgebra/correctness/testIdentity.good

@@ -0,0 +1,2 @@
+true
+false

test/library/packages/LinearAlgebra/correctness/testZero.chpl

@@ -0,0 +1,13 @@
+use LinearAlgebra;
+
+
+config const n = 100;
+config const m = 200;
+
+var A = Matrix(n,m,eltType=int(64));
+
+writeln(isZero(A));
+
+var B = eye(n);
+writeln(isZero(B));
+

test/library/packages/LinearAlgebra/correctness/testZero.good

@@ -0,0 +1,2 @@
+true
+false