Arithmetic Expressions

My Linux Learning Path

Do Linux to learn Linux.

1. Define a variable (var1) equal to 3.141516 and print var1.
2. Define var2=10*var1. Print var2.
3. Define var3=var1+var2. Print var3.
4. Define a script and use parameter arguments (two float numbers only) and print:
   • Increase by 0.98 the first value.
   • Increase by one previous result.
   • Increase by 18.0123 the second value.
   • Decrease by one previous result.
   • Addition.
   • Subtraction.
   • Multiplication.
   • Division.
   • Modulo.
   • First value raised to the second value.
5. Repeat previous exercise but this time assign the result to a fictitious variable. Use parameter expansion to create the variables.
6. Double parenthesis (arithmetic expansion) deals only with integers. In terminal solve the following:
   • Define var3=12
   • Define var4=31
   • Print var3 + var4.
   • Print var3 - var4.
   • Increase by 1 and print var3
   • Decrease by 1 and print var4
7. Create a script that ask user to insert tow integer numbers (only) and perform previous operations.
8. Explain how the following works:
   • Want to get 5.

     (( var1=$1 ))
     (( var2=$2 ))
     
     (( var1 ++ ))
     (( var2 -- ))
     
     echo "Var1 + Var2 is: $(( var1 + var2 )) 
     

   • If var1=2 and var2=2 then result is:

     #!/bin/bash
     
     echo -e "Define var1: \c"
     read var1
     
     echo -e "Define var2: \c"
     read var2
     
     (( var1+=1 ))
     (( var2=var2+3 ))
     
     echo "Var1 + Var2 : $(( var1 + var2 ))"
     

   • This code calculate the present value of a zero coupon bond. Take this as an example and perform similar scripts to get use to it.

     #!/bin/bash
     
     ERROR_PARAM=3
     
     echo -e "Define Bond Principal: \c"
     read fv # Must be positive
     
     echo -e "Define intereset rate: \c"
     read int  # Must be positive and belongs to (0-1)
     
     echo -e "Define maturity: \c"
     read n  # Must be integer
     
     #Performing test
     if [[ fv -lt 0 ]]; then
             echo "Error: Negative Future Value."
             exit $ERROR_PARAM
     fi
     
     if [[ $(echo "$int < 0.0" | bc -l) -eq 1 ]] || [[ $(echo "$int > 1.0" | bc -l) -eq 1 ]]; then
             echo "Error: Interest range out of bounds."
             exit $ERROR_PARAM
     fi
     
     if [[ n -lt 0 ]]; then
             echo "Error: Negative maturity."
             exit $ERROR_PARAM
     fi
     
     rate=$(echo "(1.0+$int)" | bc -l)
     discount=$(echo "$rate^$n" | bc -l)
     pv=$(echo "scale=4; ( $fv / $discount )" | bc -l)
     
     echo "Bond price is: $pv"