Kirchoff via matrix

Schrick-Noah_Homework-5.R

@@ -35,8 +35,6 @@ bvec <- solve(A.2, yvec)
 all.equal(as.matrix(yvec), A.2 %*% bvec) # use all.equal instead of == (tols and storage type)
 # EX: identical(as.double(8), as.integer(8)) returns FALSE
 
-
-
 # d. Plot
 poly_predict <- function(x){ 
   # given input x, returns polynomial prediction 
@@ -51,12 +49,36 @@ lines(xdomain,y.predict,type="l") # overlay solid line
 ## 3. Kirchoff
 # a. Create vectors
 # Resistance vec
-# Voltage vec
+Rvec <- c(5,10,5,15,10,20)
 # Matrix A and vector b
+A.3a <- matrix(c(Rvec[1],0,0,0,Rvec[5],Rvec[6],
+                0,Rvec[2],Rvec[3],Rvec[4],-Rvec[5],0,
+                1,-1,0,0,-1,0,
+                0,1,-1,0,0,0,
+                0,0,1,-1,0,0,
+                0,0,0,1,1,-1)
+              ,nrow=6)
+A.3a <- t(A.3a) # easier to conf that A is correct if def matrix as above then t()
+V=200
+b.3vec <- c(V,0,0,0,0,0)
+
 # Solve
-# Show currents
+i.a <- solve(A.3a,b.3vec)
+i.a
 
 # b. Repeat a. Use V=200, and R=(5,10,5,15,0,20)
+Rvec.b <- c(5,10,5,15,0,20)
+A.3b <- matrix(c(Rvec.b[1],0,0,0,Rvec.b[5],Rvec.b[6],
+                0,Rvec.b[2],Rvec.b[3],Rvec.b[4],-Rvec.b[5],0,
+                1,-1,0,0,-1,0,
+                0,1,-1,0,0,0,
+                0,0,1,-1,0,0,
+                0,0,0,1,1,-1)
+              ,nrow=6)
+A.3b <- t(A.3b) # easier to conf that A is correct if def matrix as above then t()
+
+i.b <- solve(A.3b,b.3vec)
+i.b
 
 ## 4. Schrodinger eq
 #a. Solve and plot the 1d quantum harmonic oscillator wave function