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 Author Comment/Response John Leko 10/24/00 5:24pm >Here is a function: f[x_] := 1\/8\ \((19 + 27\ x + 9\ x\^2 + x\^3)>Now I got that far to get the first and second diferentiation:Solve[f'[x]==0,x],Solve[f''[x]==0,x]. >I even managed to plot the graph. >Now what syntax do I use to get the proper y values for the x values? There are a couple of ways to do this, depending on your needs. You can: 1. Simply substitute the value into the brackets, as you would in algebra (e.g., f[3]); 2. If you have a list of specific values, use the Map command (e.g., Map[f, {3, 78, 20}]) where the second argument is your list of values; or 3. For a continuous list of values, use the Table command (e.g., Table[f[x], {x, 1, 20}]). >How do I get Mathematica to put out decimal numbers? Use N[expression]. For instance, In[13]:= f[x_] := 1/8 (19 + 27x + 9x^2 + x^3) N[Map[f, {3, 4, 5}]] Out[14]= {26., 41.875, 63.} >How can I plot specific Points such as an extreme value by markingit with a dot ? If you know the coordinates of the point, use the Point primative, e.g., Show[Graphics[Point[{1, 2}]]]; >I did not quite understand what the underline is for that one is suposed to place behind the f[x_]. The underline means pattern (section 2.3.1 in The Mathematica Book). What you are effectively doing is similar to using algebraic notation. When you say f(x) = 2x, what you are saying algebraically is that when you see an x on the righ-hand side of the equation, replace it with a particular value. The same thing happens in Mathematica, except that this pattern can be a number of different things. Not just a single value! You can, for example, replace it with another symbol... In[15]:= f[x_] := 1/8 (19 + 27x + 9x^2 + x^3) f[z] <- here I use the argument ''z'' Out[16]= (1/8 ((19 + 27 z + 9 z^2 + z^3))) Patterns are one of the features of Mathematica which give it its power, and utility. >I woul appreciate some help >best regads >Johannes URL: ,

 Subject (listing for 'basic syntax application') Author Date Posted basic syntax application Daldosch 10/24/00 06:48am Re: basic syntax application John Leko 10/24/00 5:24pm
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