Differentiate functions

[troelschristensen]

Hi.

I'm trying to programme a set of task, where the users must differentiate som functions. I have succeeded in getting this code to work, but I need eg. sin(2x), sin(x), cos(3x+3), LN(x) ....
How can I do something like these

• " If funktionsnummer = 11 Then funk = LN(x)"
• " If funktionsnummer = 12 Then funk = sin(x)"
• " If funktionsnummer = 13 Then funk = cos(2x)"
• " If funktionsnummer = 14 Then funk = x^tal1" ?
• " If funktionsnummer = 15 Then funk = tal1 * e^x" ?
• " If funktionsnummer = 16 Then funk = tal1^x ?

Can anyone help me? Hope you understand.

Kind regards
Troels

Some of my code:

Imports MathNet.Symbolics
Imports Expr = MathNet.Symbolics.SymbolicExpression

                            Dim tal1, tal2, tal3 As Integer

dropdownList28_opg1:
                            tal1 = random.Next(-10, 10)
                            tal2 = random.Next(-10, 10)
                            tal3 = random.Next(-10, 10)

                            If tal1 = 0 Or tal2 = 0 Or tal3 = 0 Then GoTo dropdownList28_opg1

                            Dim x = Expr.Variable("x")
                            Dim funktionsnummer = random.Next(1, 11)
                            Dim funk = x
                            If funktionsnummer = 1 Then funk = x
                            If funktionsnummer = 2 Then funk = tal1 * x
                            If funktionsnummer = 3 Then funk = tal1
                            If funktionsnummer = 4 Then funk = x.Pow(tal2)
                            If funktionsnummer = 5 Then funk = 1 / x
                            If funktionsnummer = 6 Then funk = x.Pow(tal1)
                            If funktionsnummer = 7 Then funk = tal1 * (x * x * x) + tal2 * x + tal3
                            If funktionsnummer = 8 Then funk = tal1 * (x * x) + tal2 * x
                            If funktionsnummer = 9 Then funk = tal1 * (x * x) + tal2
                            If funktionsnummer = 10 Then funk = tal1 * x + tal2

                            Dim afledtfunk = funk.Differentiate(x)

[troelschristensen]

Almost solved this on my own.
Used x.sin, x.cos...

But cant figur out e^x or how to chance the order of the expressions. Eg 3x^2 + 3x + 2 it writes 2 + 3x + 3x^2. Can't it be the other way around?