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+//chapter12
+//example12.21
+//page257
+
+V_CC=10 // V
+R1=12 // kilo ohm
+R2=2.7 // kilo ohm
+V_BE=0.7 // V
+R_E=180d-3 // kilo ohm
+R_C=620d-3 // kilo ohm
+
+V2=V_CC*R2/(R1+R2)
+I_E=(V2-V_BE)/R_E
+I_C=I_E
+V_CE=V_CC-I_C*(R_C+R_E)
+
+printf("the operating point is %.3f V and %.3f mA \n",V_CE,I_C)
+if V_CE<V_CC/2+0.1 | V_CE>V_CC/2-0.1  // check if V_CE is nearly half of V_CC
+    printf("circuit is mid-point biased \n")
+else 
+    printf("circuit is not mid-point biased. \n")
+end
+
+// the accurate answer for collector current is 6.315 mA but in book it is given as 6.33 mA