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Solving equation using mathematica

  1. Feb 25, 2012 #1
    Hello every one, I need help please...

    How to write in mathematica to solve an equation of x and y that is equal to 0,
    (i.e. y^4+2y^2x^2-15x=0)
    and let the program try all the value of x=0,1,2,3,....,10000.
    and all the value of y=0,1,2,3,....,100.

    The program should start with x=0 and try all the 100 value of y,
    and then go to the next x.

    Please help..thanks
     
  2. jcsd
  3. Feb 25, 2012 #2
    How about just some For loops:

    Code (Text):

    For[y = 0, y <= 10000, y++,
     For[x = 0, x <= 100, x++,
      If[y^4 + 2 y^2 x^2 - 15 x == 0,
        Print["My x: ", x, " my y: ", y];
        ];
      ]
     ]
     
    or FindInstance does this but I'm not sure if we can assume the function is attempting the solutions in the order you wish.

    Code (Text):

    FindInstance[
     y^4 + 2 y^2 x^2 - 15 x == 0 && 0 <= x <= 10000 && 0 <= y <= 100, {x,
      y}, Integers]
     
     
  4. Feb 25, 2012 #3
    I tried the the first one and the out put was:

    My x: 0 my y: 0

    I do not know if its checked all the values correctly?
    how to make it print for example on each 50x

    x=50 no solutions
    x=100 no solutions
    x=150 no solutions
    .
    .
    .
     
  5. Feb 27, 2012 #4
    Perhaps you can learn how to use If and Mod to print diagnostic messages.

    In[1]:= numsolutions=0;
    For[y=0,y<=10000,y++,
    For[x=0,x<=100,x++,
    If[y^4+2 y^2 x^2-15 x==0,numsolutions++;Print["My x: ",x," my y: ",y];];
    If[Mod[y,50]==0&&Mod[x,50]==0, Print["y=",y," x=",x, " ", numsolutions," solutions"]];
    ]
    ]

    From In[1]:= My x: 0 my y: 0
    From In[1]:= y=0 x=0 1 solutions
    From In[1]:= y=0 x=50 1 solutions
    From In[1]:= y=0 x=100 1 solutions
    From In[1]:= y=50 x=0 1 solutions
    From In[1]:= y=50 x=50 1 solutions
    From In[1]:= y=50 x=100 1 solutions
    From In[1]:= y=100 x=0 1 solutions
     
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