From: Andrey Miroshnikov <andrey@technepisteme.xyz>
Date: Tue, 17 Oct 2023 10:13:28 +0000 (+0000)
Subject: Matrix example
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=d559ce5ac28615cc5dbbb2cb57a66a2374f341ad;p=libreriscv.git

Matrix example
---

diff --git a/openpower/sv/cookbook/remap_matrix.mdwn b/openpower/sv/cookbook/remap_matrix.mdwn
index 208164f35..406fda611 100644
--- a/openpower/sv/cookbook/remap_matrix.mdwn
+++ b/openpower/sv/cookbook/remap_matrix.mdwn
@@ -36,7 +36,8 @@ and Y, result Z shown for completeness.
 
 Matrix X has 2 rows, 3 columns (2x3), and matrix Y has 3 rows, 2 columns.
 
-To determine the final dimensions of the resultant matrix Z, take the number of rows from matrix X (2) and number of columns from matrix Y (2).
+To determine the final dimensions of the resultant matrix Z, take the number
+of rows from matrix X (2) and number of columns from matrix Y (2).
 
 For the algorithm, assign indeces to matrices as follows:
 
@@ -49,15 +50,30 @@ For the algorithm, assign indeces to matrices as follows:
     Index |  0  1   2   3 |
     Mat Z | 52 58 100 112 |
 
-The method usually taught in linear algebra course to students is the following:
+(Start with the first row, then assign index left-to-right, top-to-bottom.)
 
-1. Start with the first row of the first matrix, and first column of the second matrix.
-2. Multiply each element in the row by each element in the column, and sum the result.
-3. Store result in the first row, first column entry.
+The method usually taught in linear algebra course to students is the
+following:
 
-Equation: (TODO)
+1. Start with the first row of the first matrix, and first column of the
+second matrix.
+2. Multiply each element in the row by each element in the column, and sum
+with the current value of the result matrix element (multiply-add-accumulate).
+Store result in the first row, first column entry.
+3. Move to the next column of the second matrix, and next column of the result
+matrix. If there are no more columns in the second matrix, go back to first
+column (second matrix), and move to next row (first and result matrices).
+If there are no more rows left, result matrix has been fully computed.
+4. Repeat step 2.
+4. Move to the next row of the first matrix, and next column of the second matrix.
+
+This for-loop uses the indeces as shown above
+
+    for i in range(mat_X_num_rows):
+        for k in range(0, mat_Y_num_cols):
+            for j in range(0, mat_X_num_cols): # or mat_Y_num_rows
+                mat_Z[i][k] += mat_X[i][j] * mat_Y[j][k]
 
-    A(i, j) * B(j, k) = C(i, k)
 
 Calculations:
 
@@ -73,6 +89,8 @@ Calculations:
     | 3 4 5 | * |  8  9 |   | 100 112 |
                 | 10 11 |
 
+
+
 ## Appendix
 
 ### Links