add helper transpose

Author: kmolan

src/numerical_derivative/hessian.rs

@@ -7,6 +7,11 @@ use num_complex::ComplexFloat;
 /// Returns the hessian matrix for a given function
 /// Can handle multivariable functions of any order or complexity
 /// 
+/// The 2-D matrix returned has the structure [[d2f/d2var1, d2f/dvar1*dvar2, ... , d2f/dvar1*dvarN], 
+///                                            [                   ...                            ], 
+///                                            [d2f/dvar1*dvarN, d2f/dvar2*dvarN, ... , dfM/d2varN]]
+/// where 'N' is the total number of variables
+/// 
 /// assume our function is y*sin(x) + 2*x*e^y. First define the function
 /// ```
 /// use multicalc::numerical_derivative::hessian;

src/numerical_derivative/jacobian.rs

@@ -6,6 +6,14 @@ use num_complex::ComplexFloat;
 /// Returns the jacobian matrix for a given vector of functions
 /// Can handle multivariable functions of any order or complexity
 /// 
+/// The 2-D matrix returned has the structure [[df1/dvar1, df1/dvar2, ... , df1/dvarN],
+///                                            [         ...              ], 
+///                                            [dfM/dvar1, dfM/dvar2, ... , dfM/dvarN]]
+/// 
+/// where 'N' is the total number of variables, and 'M' is the total number of functions
+/// 
+/// consult the helper utility [`multicalc::utils::helper::transpose`] to transpose the matrix shape if required
+/// 
 /// NOTE: Returns a Result<T, ErrorCode>
 /// Possible ErrorCode are:
 /// VectorOfFunctionsCannotBeEmpty -> if function_matrix argument is an empty array

src/utils/helper.rs

@@ -0,0 +1,18 @@
+use num_complex::ComplexFloat;
+
+///utility to convert the transpose the matrix
+///takes an input of a matrix of shape MxN, and returns the matrix as NxM
+pub fn transpose<T: ComplexFloat, const NUM_ROWS: usize, const NUM_COLUMNS: usize>(matrix: &[[T; NUM_COLUMNS]; NUM_ROWS]) -> [[T; NUM_ROWS]; NUM_COLUMNS]
+{
+    let mut result = [[T::zero(); NUM_ROWS]; NUM_COLUMNS];
+
+    for row_index in 0..NUM_COLUMNS
+    {
+        for col_index in 0..NUM_ROWS
+        {
+            result[row_index][col_index] = matrix[col_index][row_index];
+        }
+    }
+
+    return result;
+}

src/utils/mod.rs

@@ -1,2 +1,6 @@
 pub mod gl_table;
-pub mod error_codes;
+pub mod error_codes;
+pub mod helper;
+
+#[cfg(test)]
+mod test;

src/utils/test.rs

@@ -0,0 +1,17 @@
+use crate::utils::helper;
+
+#[test]
+fn test_transpose_1() 
+{
+    let original = [[1.0, 2.0, 3.0, 4.0], [1.0, 4.0, 6.0, 8.0], [1.0, 6.0, 9.0, 12.0]];
+
+    let trans = helper::transpose(&original);
+
+    for i in 0..original.len()
+    {
+        for j in 0..original[0].len()
+        {
+            assert!(original[i][j] == trans[j][i]);
+        }
+    }
+}