beginner's struggle with programming

Questions
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1

Hi,

I am trying to teach my self programming with mathematica and this is one of my first attempts. I am trying to solve x1, x2, x3, x4 and x5 for different values of S, x, y, and ?, given by the following equations:

 x1 = 2*S+x*y/?
 x2 = S+?/x*y
 x3 = 2*?+x*y/S
 x4= x*x3 + y*x1 + ?*x2
 x5= x1/x2

I tried to do it by using Manipulate i.e.

Manipulate[
  N[x1 = 2*S+x*y/?, {S, 150, 1000, 
   50}, {x, 1, 10, 1}, {y, 1, 10, 1}, {?, 2, 4, 1}];
Manipulate[
  N[ x2 = S+?/x*y, {S, 150, 1000, 
   50}, {x, 1, 10, 1}, {y, 1, 10, 1}, {?, 2, 4, 1}];
Manipulate[
  N[x3 = 2*?+x*y/S, {S 150, 1000, 
   50}, {x, 1, 10, 1}, {y, 1, 10, 1}, {?, 2, 4, 1}];
Manipulate[
  N[x4 = x*x2*x3 + y*x1*x3 + ?* x1*x2], {x, 1, 10, 1}, {y, 1, 10, 
   1}, {?, 2, 4, 1}];
Manipulate[
 N[x5= x1/x2], {S, 150, 1000,50}, {x, 1, 10, 1}, {y, 1, 10, 
  1}, {?, 2, 4, 1}]

However, this is not a very efficient way. Any suggestions?

In addition I would like to plot in 2D S vs. x1, x2, and x3 (x-axis S and y- axis x1, x2, and x3). S is in kg and x1, x2, x3 is in meters.

thank you in advance for your help.

2

Make sure you know the difference between a definition := , an assignment = , a rule → , and mathematical equal ==
like

equation1 = x1==2*S;

or define a function

x1[s_, a_] := 5 s + a^2;

Manipulate[x1[s, a], {s, 0, 1.}, {a, -1, 1}]

Plot[x1[s, 3], {s, 0, 1.}]

There are nice tutorials on the Wolfram website.

3

Hi Kay,

thank you very much for your advice. However, my problem is more on how to be able to, let’s say, visualize the results rather than solving.

I have managed to solve them, but I would like to make a programm where every time i update the input variables (S, x, y, and ?) the ouput is also updated creating a 2D plot.

I hope you understand what I mean.