Completely new and am SO confused

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Huzapro2
Posts: 1
Joined: Aug 02, 2011 23:36

Completely new and am SO confused

Postby Huzapro2 » Aug 02, 2011 23:45

OK so hello everyone! this is my first time ever using any programming program other than what is available on a Ti84... my programming skils currently are limited to math equations in which each variable has to be prompted for, and given explicite directions to follow in the code itself.

I was wondering if it were at all possible to create a program in which all you had to do was type in an equation, and it would solve it for you. this means im looking for something that would allow you to enter 2+2, and it would give you 4. this is opposed to what I have taught myself today how to do, which is for the program to prompt you on what operation you would like to do, and then for each variable (2 and 2), then would go through the code it has and adds the two variables together... this is extremely complicated, long and difficult for usage... is what im asking for possible?
Richard
Posts: 2999
Joined: Jan 15, 2007 20:44
Location: Australia

Postby Richard » Aug 03, 2011 1:14

There are complex ways of doing it, but this is quick and dirty.

Code: Select all

' Pack an expression into an envelope, compile, run then get the result
Dim As String expression    ' a numerical expression
Input "Enter expression.";expression
Dim As String program = $"C:\FreeBASIC\fbc.exe "    ' the FB compiler

' create a FreeBASIC program
Open "scratch.bas" For Output As #1
Print #1, "open "; """scratch.txt"""; " for output as #2"
Print #1, "print #2, "; expression
Print #1, "close #2"
Close #1

' compile the scratch.bas program file
If Exec( program, " scratch.bas" ) <> 0 Then Print "Compile failure"

' run the exe program generated
If Exec( "scratch.exe", "" ) <> 0 Then Print "Execute failure"

' now get the result from the output file
Open "scratch.txt" For Input As #1
Dim As String result
Line Input #1, result
Close #1
Print "Result = ";result

Sleep
dodicat
Posts: 6378
Joined: Jan 10, 2006 20:30
Location: Scotland

Re: Completely new and am SO confused

Postby dodicat » Aug 03, 2011 1:15

Huzapro2 wrote:OK so hello everyone! this is my first time ever using any programming program other than what is available on a Ti84... my programming skils currently are limited to math equations in which each variable has to be prompted for, and given explicite directions to follow in the code itself.

I was wondering if it were at all possible to create a program in which all you had to do was type in an equation, and it would solve it for you. this means im looking for something that would allow you to enter 2+2, and it would give you 4. this is opposed to what I have taught myself today how to do, which is for the program to prompt you on what operation you would like to do, and then for each variable (2 and 2), then would go through the code it has and adds the two variables together... this is extremely complicated, long and difficult for usage... is what im asking for possible?


There are quite a few parsers available in Freebasic for doing this, here is one of them.

Code: Select all


' ***********  START OF _EVAL **********************************
Dim Shared e_input    As String 
Dim Shared e_tok      As String 
Dim Shared e_spelling As String 
Dim Shared e_error    As Integer
Dim Shared x As Double           'x,y or z substitutes as a number in an expression
dim shared y as double
dim shared z as double

FUNCTION SEC(byval x AS DOUBLE) AS DOUBLE
    SEC = 1 / COS(x)
END FUNCTION

FUNCTION COSEC(byval x AS DOUBLE) AS DOUBLE
    COSEC = 1 / SIN(x)
END FUNCTION

FUNCTION COT(byval x AS DOUBLE) AS DOUBLE
    COT = 1 / TAN(x)
END FUNCTION

FUNCTION ARCSIN(byval x AS DOUBLE) AS DOUBLE
    ARCSIN = ATN(x / SQR(-x * x + 1))
END FUNCTION

FUNCTION ARCCOS(byval x AS DOUBLE) AS DOUBLE
    ARCCOS = ATN(-x / SQR(-x * x + 1)) + 2 * ATN(1)
END FUNCTION

FUNCTION ARCSEC(byval x AS DOUBLE) AS DOUBLE
    ARCSEC = ATN(x / SQR(x * x - 1)) + SGN((x) -1) * (2 * ATN(1))
END FUNCTION

FUNCTION ARCCOSEC(byval x AS DOUBLE) AS DOUBLE
    ARCCOSEC = ATN(x / SQR(x * x - 1)) + (SGN(x) - 1) * (2 * ATN(1))
END FUNCTION

FUNCTION ARCCOT(byval x AS DOUBLE) AS DOUBLE
    ARCCOT = ATN(x) + 2 * ATN(1)
END FUNCTION

FUNCTION ARCTAN(byval x AS DOUBLE) AS DOUBLE
    ARCTAN = ATN(x)
END FUNCTION   

FUNCTION sinh(byval x AS DOUBLE) AS DOUBLE
    sinh = (EXP(x) - EXP(-x)) / 2
END FUNCTION

FUNCTION cosh(byval x AS DOUBLE) AS DOUBLE
    cosh = (EXP(x) + EXP(-x)) / 2
END FUNCTION

FUNCTION tanh(byval x AS DOUBLE) AS DOUBLE
    tanh = (EXP(x) - EXP(-x)) / (EXP(x) + EXP(-x))
END FUNCTION

FUNCTION sech(byval x AS DOUBLE) AS DOUBLE
    sech = 2 / (EXP(x) + EXP(-x))
END FUNCTION

FUNCTION cosech(byval x AS DOUBLE) AS DOUBLE
    cosech = 2 / (EXP(x) - EXP(-x))
END FUNCTION

FUNCTION coth(byval x AS DOUBLE) AS DOUBLE
    coth = (EXP(x) + EXP(-x)) / (EXP(x) - EXP(-x))
END FUNCTION

FUNCTION arcsinh(byval x AS DOUBLE) AS DOUBLE
    arcsinh = LOG(x + SQR(x * x + 1))
END FUNCTION

FUNCTION arccosh(byval x AS DOUBLE) AS DOUBLE
    arccosh = LOG(x + SQR(x * x - 1))
END FUNCTION

FUNCTION arctanh(byval x AS DOUBLE) AS DOUBLE
    arctanh = LOG((1 + x) / (1 - x)) / 2
END FUNCTION

FUNCTION arcsech(byval x AS DOUBLE) AS DOUBLE
    arcsech = LOG((SQR(-x * x + 1) + 1) / x)
END FUNCTION

FUNCTION arccosech(byval x AS DOUBLE) AS DOUBLE
    arccosech = LOG((SGN(x) * SQR(x * x + 1) +1) / x)
END FUNCTION

FUNCTION arccoth(byval x AS DOUBLE) AS DOUBLE
    arccoth = LOG((x + 1) / (x - 1)) / 2
END FUNCTION

FUNCTION LOGN(byval x AS DOUBLE,byval n AS DOUBLE) AS DOUBLE
    LOGN = LOG(x) / LOG(n)
END FUNCTION

FUNCTION HAVERSINE(byval x AS DOUBLE) AS DOUBLE
    HAVERSINE = (SIN(x/2))^2
END FUNCTION
Function e_function(fun As String, arg As Double) As Double
  Dim n As Double

  Select Case Lcase$(fun)
    Case "abs": n = Abs(arg)
    Case "atn": n = Atn(arg)
    Case "cos": n = Cos(arg)
    Case "exp": n = Exp(arg)
    Case "fix": n = Fix(arg)
    Case "int": n = Int(arg)
    Case "log": n = Log(arg)
    Case "rnd": n = Rnd(arg)
    Case "sgn": n = Sgn(arg)
    Case "sin": n = Sin(arg)
    Case "sqr": n = Sqr(arg)
    Case "tan": n = Tan(arg)
    case "haversine":n=haversine(arg)
    case "cosec":n=cosec(arg)
    case "sec":n=sec(arg)
    case "cot": n=cot(arg)
    case "arcsin":n=arcsin(arg)
    case "arccos":n=arccos(arg)
    case "arctan":n=arctan(arg)
    case "arcsec":n=arcsec(arg)
    case "arccosec":n=arccosec(arg)
    case "arccot":n=arccot(arg)
    case "sinh":n=sinh(arg)
    case "cosh":n=cosh(arg)
    case "tanh":n=tanh(arg)
    case "sech":n=sech(arg)
    case "cosech":n=cosech(arg)
    case "coth":n=coth(arg)
    case "arcsinh":n=arcsinh(arg)
    case "arccoth":n=arccoth(arg)
    case "arctanh":n=arctanh(arg)
    case "arcsech":n=arcsech(arg)
    case "arccosech":n=arccosech(arg)
    case "arccoth":n=arccoth(arg)
    Case Else
      If Not e_error Then
         'MsgBox("undefined function '" + fun + "'")
         print "UNDEFINED FUNCTION " + fun
         e_error = -1
      End If
   End Select
   e_function = n
End Function

Sub e_nxt()
  Dim is_keyword As Integer
  Dim c As String 

  e_tok = ""
  e_spelling = ""

  Do
    c = Left$(e_input, 1)
    e_input = Mid$(e_input, 2)
  Loop While c = " " Or c = Chr$(9) Or c = Chr$(13) Or c = Chr$(10)

  Select Case Lcase$(c)
  Case "0" To "9", ".","x","y","z" 'MODIFIED to support external x,y or z
      If c="x" Then c=Str(x) 
       If c="y" Then c=Str(y) 
       If c="z" Then c=Str(z)
      e_tok = "num"
      Do
        e_spelling = e_spelling + c
        c = Left$(e_input, 1)
        e_input = Mid$(e_input, 2)
      Loop While (c >= "0" And c <= "9") Or c = "." Or c="x" or c="y" 'ALTERATION *********
      e_input = c + e_input

    ' Identifier or keyword.
    Case "a" To "z", "_"
      Dim As Integer is_id
      e_tok = "id"
      Do
        e_spelling = e_spelling + c
        c = Lcase$(Left$(e_input, 1))
        e_input = Mid$(e_input, 2)
        is_id = (c >= "a" And c <= "z")
        is_id = is_id Or c = "_" Or (c >= "0" And c <= "9")
      Loop While is_id
      e_input = c + e_input

      is_keyword = -1
      Select Case Lcase$(e_spelling)
        Case "and"
        Case "eqv"
        Case "imp"
        Case "mod"
        Case "not"
        Case "or"
        Case "xor"
        Case Else: is_keyword = 0
      End Select
      If is_keyword Then
         e_tok = Lcase$(e_spelling)
      End If

    Case "<", ">"
      e_tok = c
      c = Left$(e_input, 1)
      If c = "=" Or c = ">" Then
         e_tok = e_tok + c
         e_input = Mid$(e_input, 2)
      End If

    Case Else
      e_tok = c
  End Select

  If e_spelling = "" Then
    e_spelling = e_tok
  End If
End Sub

Sub e_match (token As String)
  If Not e_error And e_tok <> token Then
    print "EXPECTED " + token + ", got '" + e_spelling + "'"
    e_error = -1
  End If
  e_nxt
End Sub

Function e_prs (p As Integer) As Double
   Dim n   As Double 
   Dim fun As String 
   If e_tok = "num" Then
      ' number.
      n = Val(e_spelling)
      e_nxt
   Elseif e_tok = "-" Then
      e_nxt
      n = -e_prs(11) 
   Elseif e_tok = "not" Then
      e_nxt
      n = Not e_prs(6) 
   Elseif e_tok = "(" Then
      e_nxt
      n = e_prs(1)
      e_match(")")
   Elseif e_tok = "id" Then
      fun = e_spelling
      e_nxt
      e_match("(")
      n = e_prs(1)
      e_match(")")
      n = e_function(fun, n)
   Else
      If Not e_error Then
         print "syntax error, token = '" + e_spelling + "'"
         e_error = -1
      End If
   End If

  Do While Not e_error
    If     p <= 11 And e_tok = "^"   Then
      e_nxt: n = n ^ e_prs(12)
    Elseif p <= 10 And e_tok = "*"   Then
      e_nxt: n = n *   e_prs(11)
    Elseif p <= 10 And e_tok = "/"   Then
      e_nxt: n = n /   e_prs(11)
    Elseif p <= 9  And e_tok = ""   Then
      e_nxt: n = n \   e_prs(10)
    Elseif p <= 8  And e_tok = "mod" Then
      e_nxt: n = n Mod e_prs(9)
    Elseif p <= 7  And e_tok = "+"   Then
      e_nxt: n = n +   e_prs(8)
    Elseif p <= 7  And e_tok = "-"   Then
      e_nxt: n = n -   e_prs(8)
    Elseif p <= 6  And e_tok = "="   Then
      e_nxt: n = n =   e_prs(7)
    Elseif p <= 6  And e_tok = "<"   Then
      e_nxt: n = n <   e_prs(7)
    Elseif p <= 6  And e_tok = ">"   Then
      e_nxt: n = n >   e_prs(7)
    Elseif p <= 6  And e_tok = "<>"  Then
      e_nxt: n = n <>  e_prs(7)
    Elseif p <= 6  And e_tok = "<="  Then
      e_nxt: n = n <=  e_prs(7)
    Elseif p <= 6  And e_tok = ">="  Then
      e_nxt: n = n >=  e_prs(7)
    Elseif p <= 5  And e_tok = "and" Then
      e_nxt: n = n And e_prs(6)
    Elseif p <= 4  And e_tok = "or"  Then
      e_nxt: n = n Or  e_prs(5)
    Elseif p <= 3  And e_tok = "xor" Then
      e_nxt: n = n Xor e_prs(4)
    Elseif p <= 2  And e_tok = "eqv" Then
      e_nxt: n = n Eqv e_prs(3)
    Elseif p <= 1  And e_tok = "imp" Then
      e_nxt: n = n Imp e_prs(2)
    Else
      Exit Do
    End If
  Loop
  e_prs = n
End Function


Function e_eval(Byval s As String,Byref value As Double) As Integer
   e_error = 0
   e_input = s
   e_nxt
   value = e_prs(1)
   If e_tok <> "" And Not e_error Then
      print "syntax error, token = '" + e_spelling + "'"
      e_error = -1
   End If

   e_eval = Not e_error
End Function
function _EVAL(_exp as string) as double
    dim ans as double
   e_eval(_exp,ans)
   return ans
end function
'___________ END OF _EVAL ___________________________

'USAGE

dim as string s
do
input "enter equation (or q to quit) ";s
if s="q" then exit do
print s;" = ";_eval(s)
loop

'part 2
cls
do
print "Example of an equation in the variable x ---> sin(x)+3*cos(3*x)"
print
input "enter an x value) ";x

input "Enter an equation in x (or q to quit)   ",s
if s="q" then exit do
print s;" = ";_eval(s);" when x= ";x
loop



dafhi
Posts: 1334
Joined: Jun 04, 2005 9:51

Postby dafhi » Aug 03, 2011 8:58

you guys were all over that like dobermans on a tossed sausage link
fxm
Posts: 9558
Joined: Apr 22, 2009 12:46
Location: Paris suburbs, FRANCE

Postby fxm » Aug 03, 2011 9:11

dafhi wrote:you guys were all over that like dobermans on a tossed sausage link
Yes but the Doberman eats not only the sausages but also the one who throws them, which is not the case in this forum.
Their members are both hungry for topics to discuss and supports to give.
dafhi
Posts: 1334
Joined: Jun 04, 2005 9:51

Postby dafhi » Aug 03, 2011 9:58

correct me if I am wrong, but are you asking how you can type in an equation and get the answer?

many modern programming languages have a built-in parser

For example in Freebasic,

Code: Select all

Print (2 + 2) / 2

Sleep
Richard
Posts: 2999
Joined: Jan 15, 2007 20:44
Location: Australia

Postby Richard » Aug 03, 2011 11:09

@ dafhi.
We had both seen the problem before so we had the code to post. And yes, the FB forum is a dangerous place to post if you want to write your own original code.

There is a fundamental difference between “compile time” and “runtime”.
“Compile time” parsing is trivial in FB, but “Runtime” requires a coded parser.
It appears that Huzapro2 is wanting a “runtime” calculator facility, we gave two possible solutions.

Richard's solution uses the parser within the FB Compiler by writing another small FB program.

Dodicat's solution provides the parser as FB code which is more involved, but probably better in the long run as the FB compiler does not need to remain available once the main.exe is generated.
kiyotewolf
Posts: 1009
Joined: Oct 11, 2008 7:42
Location: ABQ, NM
Contact:

Postby kiyotewolf » Aug 13, 2011 6:43

my first time ever using any programming program other than what is available on a Ti84


Oh wow, you're going from Heiroglyphics flavor of 'BASiC' to something far different.

In TI-84, they use triangles, and little 45 degree angle signs, what you might wanna do is look up DARTMOUTH BASIC and go over a *.PDF of what BASIC looks like away from a pocket calculator, then just look up any reference material on any flavor of BASIC.

There are some excellent examples of parsers in the forum already which will evaluate equations, even graph them, so just poke around.

Variable solving, graphing, parsers, parsing, use the SEARCH button and just look around. There's lots to see.



~Kiyote!

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