computeA

1 files changed, 32 insertions, 0 deletions

diff --git a/computeA.m b/computeA.m
new file mode 100755
index 0000000..aa1ca08
--- /dev/null
+++ b/computeA.m
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+function [ A ] = computeA( C, X, Y, Sx, Sy )
+% computes the A matrix for solving a truss
+    
+    [j, m] = size(C);
+    A = zeros(2*j, m+3);
+    for row = 1:j 
+        for col = 1:m
+            if C(row,col)
+                p = findother(C(:,col), row);
+                p1 = [X(row), Y(row)];
+                p2 = [X(p), Y(p)];
+                d = distance(p1, p2);
+                A(row,col) = (X(p) - X(row))/d;
+                A(row+j,col) = (Y(p) - Y(row))/d;
+            end
+        end
+    end
+    A(m+1:m+3,1:j)=Sx;
+    A(m+1:m+3,j+1:2*j)=Sy;
+end
+
+function [ p ] = findother(col, row)
+    for i = 1:size(col)
+        if col(i) ~= row && col(i)
+            p = i;
+        end
+    end
+end
+
+function [ d ] = distance( p1, p2 )
+    d = sqrt((p1(1)-p2(1))^2 + (p1(2)-p2(2))^2);
+end
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