avoid division by zero

SciRuby · Mar 23, 2015 · 2671b10 · 2671b10
1 parent 0b48061
commit 2671b10
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Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/ext/nmatrix/math.cpp b/ext/nmatrix/math.cpp
@@ -435,6 +435,10 @@ namespace nm {
 
       if (M == 2) {
         DType det = A[0] * A[lda+1] - A[1] * A[lda];
+        if (det == 0) {
+          rb_raise(nm_eNotInvertibleError, 
+              "matrix must have non-zero determinant to be invertible (not getting this error does not mean matrix is invertible if you're dealing with floating points)");
+        }
         B[0] = A[lda+1] / det;
         B[1] = -A[1] / det;
         B[ldb] = -A[lda] / det;
@@ -445,7 +449,8 @@ namespace nm {
         DType det;
         det_exact<DType>(M, A_elements, lda, reinterpret_cast<void*>(&det));
         if (det == 0) {
-          rb_raise(nm_eNotInvertibleError, "matrix must have non-zero determinant to be invertible (not getting this error does not mean matrix is invertible if you're dealing with floating points)");
+          rb_raise(nm_eNotInvertibleError, 
+              "matrix must have non-zero determinant to be invertible (not getting this error does not mean matrix is invertible if you're dealing with floating points)");
         }
 
         B[0]      = (  A[lda+1] * A[2*lda+2] - A[lda+2] * A[2*lda+1]) / det; // A = ei - fh

diff --git a/lib/nmatrix/math.rb b/lib/nmatrix/math.rb
@@ -119,7 +119,6 @@ def invert lda=nil, ldb=nil
       if self.integer_dtype?
         __inverse_exact__(inverse.cast(dtype: :rational128), lda, ldb)
       else
-        dtype = self.dtype
         __inverse_exact__(inverse, lda, ldb)
       end
     end