proble in using "solve function

i am using solve function to equate two equations but the result are not the one that i want and also have problem with the format of the result . the exp. is

[L D] = solve(L*(D-d)==0.1386,L/(D-d)==3.6,'Real',true)

==============

the result is in fraction form or some times show empty matrix

[Walter Roberson]

L = (9/250)*sqrt(385),  D = (1/100)*sqrt(385)+d
L = -(9/250)*sqrt(385), D = -(1/100)*sqrt(385)+d

Answer 1

[Mischa Kim]

Have you assigned a numeric value for d ?

syms L D
d = 1;
[L D] = solve(L*(D-d)==0.1386,L/(D-d)==3.6,'Real',true)
L =
 385^(1/2)/100 + 1
 1 - 385^(1/2)/100
D =
  (9*385^(1/2))/250
 -(9*385^(1/2))/250

double(L(1))
ans =
   1.196214168703486

[vikas]

i have assigned value for d=0.1382 and i am getting the results same as yours but i want to get results in the format "double(L(1))" without using this code

Answer 2

[Walter Roberson]

double(L), double(D)

And see http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F

[Walter Roberson]

replace

syms L D

with

L = sym('L', 'd');
D = sym('D', 'd');

[vikas]

when i used * L=sym('L','positive'); D=sym('D','positive'); solve(L*(D-d)-Aw,L/(D-d)-3.6,'Real',true) *

i got result

ans =

    D: [1x1 sym]
    L: [1x1 sym]
i have to select only one value of L and D which are dimensions

[Walter Roberson]

S = solve(L*(D-d)-Aw,L/(D-d)-3.6,'Real',true);
S.D
S.L

and if appropriate,

double(S.D)
double(S.L)