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Moderate clean-up

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edited Jun 25, 2014 at 0:25

108.1k
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Solve[ ] Solve works with numbers but not number stored in variable

So I have the code:

theta = 0.1; phi = 0.1;
a = 1 - 3 Sin[theta]^2*Cos[phi]^2;
b = 1 - 3 Sin[theta]^2*Cos[phi - (2 Pi/3)]^2;
c = 1 - 3 Sin[theta]^2*Cos[phi - (4 Pi/3)]^2;
Solve[a*b*Sin[Solve[
  a*b*Sin[(Sqrt[3] x - 3 y)/2] == 
  a*c*Sin[(Sqrt[3] x + 3 y)/2] == 
  -b*c*Sin[Sqrt[3] x], 
  {x, y}]

which I left running for 10 minutes before aborting. However if I simply replace the constants with their numerical values, aka I replace the last line above by

Solve[0Solve[
  0.965496 Sin[(Sqrt[3] x - 3 y)/2] == 
  0.960503 Sin[(Sqrt[3] x + 3 y)/2] == 
  -0.984803 Sin[Sqrt[3] x], 
  {x, y}]

itThe above runs straight away with no problems. I don't understand why it is doing this. Any pointers? As always thanks a bunch for any help :)

Solve[ ] works with numbers but not number stored in variable

So I have the code:

theta = 0.1; phi = 0.1;
a = 1 - 3 Sin[theta]^2*Cos[phi]^2;
b = 1 - 3 Sin[theta]^2*Cos[phi - (2 Pi/3)]^2;
c = 1 - 3 Sin[theta]^2*Cos[phi - (4 Pi/3)]^2;
Solve[a*b*Sin[(Sqrt[3] x - 3 y)/2] == a*c*Sin[(Sqrt[3] x + 3 y)/2] == -b*c*Sin[Sqrt[3] x], {x, y}]

which I left running for 10 minutes before aborting. However if I simply replace the constants with their numerical values, aka I replace the last line above by

Solve[0.965496 Sin[(Sqrt[3] x - 3 y)/2] == 0.960503 Sin[(Sqrt[3] x + 3 y)/2] == -0.984803 Sin[Sqrt[3] x], {x, y}]

it runs straight away with no problems. I don't understand why it is doing this. Any pointers? As always thanks a bunch for any help :)

Solve works with numbers but not number stored in variable

I have the code:

theta = 0.1; phi = 0.1;
a = 1 - 3 Sin[theta]^2*Cos[phi]^2;
b = 1 - 3 Sin[theta]^2*Cos[phi - (2 Pi/3)]^2;
c = 1 - 3 Sin[theta]^2*Cos[phi - (4 Pi/3)]^2;
Solve[
  a*b*Sin[(Sqrt[3] x - 3 y)/2] == 
  a*c*Sin[(Sqrt[3] x + 3 y)/2] == 
  -b*c*Sin[Sqrt[3] x], 
  {x, y}]

which I left running for 10 minutes before aborting. However if I simply replace the constants with their numerical values, aka I replace the last line above by

Solve[
  0.965496 Sin[(Sqrt[3] x - 3 y)/2] == 
  0.960503 Sin[(Sqrt[3] x + 3 y)/2] == 
  -0.984803 Sin[Sqrt[3] x], 
  {x, y}]

The above runs straight away with no problems. I don't understand why it is doing this. Any pointers?

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asked Jun 24, 2014 at 21:54

Tom

3.4k
1
18
35

Solve[ ] works with numbers but not number stored in variable

So I have the code:

theta = 0.1; phi = 0.1;
a = 1 - 3 Sin[theta]^2*Cos[phi]^2;
b = 1 - 3 Sin[theta]^2*Cos[phi - (2 Pi/3)]^2;
c = 1 - 3 Sin[theta]^2*Cos[phi - (4 Pi/3)]^2;
Solve[a*b*Sin[(Sqrt[3] x - 3 y)/2] == a*c*Sin[(Sqrt[3] x + 3 y)/2] == -b*c*Sin[Sqrt[3] x], {x, y}]

which I left running for 10 minutes before aborting. However if I simply replace the constants with their numerical values, aka I replace the last line above by

Solve[0.965496 Sin[(Sqrt[3] x - 3 y)/2] == 0.960503 Sin[(Sqrt[3] x + 3 y)/2] == -0.984803 Sin[Sqrt[3] x], {x, y}]

it runs straight away with no problems. I don't understand why it is doing this. Any pointers? As always thanks a bunch for any help :)

equation-solving