Imlemented by Abinash Singh During FOSSEE Semester Long Fellowship 2024

1 files changed, 55 insertions, 24 deletions

diff --git a/macros/fftn.sci b/macros/fftn.sci
index b8b4170..c90b096 100644
--- a/macros/fftn.sci
+++ b/macros/fftn.sci
@@ -1,26 +1,57 @@
+/*Description:
+        This function computes the N-dimensional discrete Fourier transform of A using a Fast Fourier Transform (FFT) algorithm.
+        The optional vector argument SIZE may be used to specify the dimensions of the array to be used.
+        If an element of SIZE is smaller than the corresponding dimension of A, then the dimension of A is truncated prior to performing the FFT.
+        Otherwise, if an element of SIZE is larger than the corresponding dimension, then A is resized and padded with zeros.
+  Calling sequence:
+         Y = fftn(A)
+         Y = fftn(A, SIZE)
+  Parameters:
+        A: Matrix, the input data for which the FFT is computed.
+        SIZE: Optional vector specifying the dimensions of the output array. If provided, the dimensions of A are adjusted accordingly.
+  Examples:
+        fftn([6 9 7 ;2 9 9 ;0 3 1],[2 2])
+        ans  =
+        26.  -10.
+        4.    4. 
+ */
 function y = fftn(A, SIZE)
-//This function computes the N-dimensional discrete Fourier transform of A using a Fast Fourier Transform (FFT) algorithm.
-//Calling Sequence
-//Y = fftn(A)
-//Y = fftn(A, size)
-//Parameters
-//A: Matrix 
-//Description
-//This function computes the N-dimensional discrete Fourier transform of A using a Fast Fourier Transform (FFT) algorithm. The optional vector argument SIZE may be used specify the dimensions of the array to be used.  If an element of SIZE is smaller than the corresponding dimension of A, then the dimension of A is truncated prior to performing the FFT.  Otherwise, if an element of SIZE is larger than the corresponding dimension then A is resized and padded with zeros.
-//Examples
-//fftn([2,3,4])
-//ans = 
-//     9.  - 1.5 + 0.8660254i  - 1.5 - 0.8660254i  
-funcprot(0);
-rhs = argn(2)
-if(rhs<1 | rhs>2)
-error("Wrong number of input arguments.");
-end
-
-	select(rhs)
-	case 1 then
-	y = callOctave("fftn",A);
-	case 2 then
-	y = callOctave("fftn",A, SIZE);
-	end
+    funcprot(0);
+    // Get the number of input arguments
+    rhs = argn(2);
+    // Check if the number of input arguments is valid
+    if rhs < 1 | rhs > 2 then
+        error("Wrong number of input arguments.");
+    end
+    // Perform action based on the number of input arguments
+    switch rhs
+    case 1 // If only A is provided
+        y = fft(A);
+    case 2 // If both A and SIZE are provided
+        // Check if A needs resizing
+        if size(A) == SIZE then
+            // No resizing needed
+            break;
+        elseif length(size(A)) ~= length(SIZE) then
+            error("Output size must have at least Ndims");
+        else
+            // Resize A using the resize_matrix function
+            A = resize_matrix(A, SIZE);
+        end
+        y = fft(A);
+    end
 endfunction
+/*
+//test cases
+i=%i;tol = 0.00001; pi = %pi ;
+//test 1
+Y = [41.0000 + 0*i ,-2.5000 +  2.5981*i ,-2.5000 -  2.5981*i ;2.0000 +  8.6603*i  ,  2.0000 +  3.4641*i  , -8.5000 + 11.2583*i ;2.0000 -  8.6603*i  , -8.5000 - 11.2583*i ,   2.0000 -  3.4641*i]
+assert_checkalmostequal(fftn([3 7 5;0 1 7;9 5 4]),Y,tol)
+// test
+assert_checkalmostequal(fftn([100 278;334 985]),[1697,-829;-941,473],tol)
+assert_checkalmostequal(fftn([2:5;8 7 5 1;7 3 4 5;0 0 1 6],[2 2]),[20,0;-10,-2],tol)
+assert_checkalmostequal(fftn([[i 2+3*i 2+pi;pi i+2 pi+i;1 5+2*5*i pi+10*i]],[2,2]),[7.1416 + 5.0000*i , -0.8584 - 3.0000*i; -3.1416 + 3.0000*i , -3.1416 - 1.0000*i],tol)
+//error
+fftn([2:5;8 7 5 1;7 3 4 5;0 0 1 6],[2]);
+*/
+