[RESOLVED] Expression Calculator

[dbasnett]

Recently we had reason to use an infix calculator I wrote. During testing two questions came up and I' seeking other opinions.

The first was concerning expressions like -9^2. What does that equal? Pumping that into the Google search bar or Wolfram Alpha it equals -81.
But it appears that both interpret that to mean -(9^2).

The second question was my implementation of multiplication by juxtaposition, especially my giving it a higher precedence than regular multiplication. e.g.

6/2(2+1) = 1 multiplication by juxtaposition
6/2*(2+1)=9

For those unfamiliar with multiplication by juxtaposition here is an explanation.

https://www.youtube.com/watch?v=lLCDca6dYpA


In the section labeled ‘Current Calculators’ in the link below it seems that not all calculators answer the same.

https://www.youtube.com/watch?v=4x-BcYCiKCk


Here are all of the test ran. Format is expression TAB answer. All numbers represented by decimal.

6/2(2+1)	1
6/2*(2+1)	9
84/14*9/18	3
22/7	3.1428571428571428571428571429
7(3.1428571428571428571428571427)	21.999999999999999999999999999
-4(2+3)/(8-6)	-10
-4(2-3^2)/(8-6)	14
3-5^2	-22
3(2+5)	21
3/3(2+5)	0.1428571428571428571428571429
3/3*(2+5)	7
4*3(4-2(6-3))/3	-8
(8-6)+10	12
(5*9)/(10+5)	3
(8*8)-(11*4)	20
((40*2)-10)/5	14
(16*6)+(30+5)	131
56-25-12/48-29	1.75
20*5-12*5*60-55	-3555
(20*5-12*5*60-55)%10	-5
-1^2	1
-2^2	4
-(2^2)	-4
0-3^2	-9
-3^5	-243
3^-2	0.111111111111111
-3^-2	0.111111111111111
0.5^3	0.125
-0.5^3	-0.125
1,000^2	1000000
√0	0
√24	4.89897948556636
sqrt(24)	4.89897948556636

Math.Pow Test

        For d As Double = 1.0# To 5.0# Step 1.0#
            Dim ans As Double = Math.Pow(-2.0#, d)
            Debug.WriteLine("-2 raised to {0} = {1}?", d, ans)
        Next