yes.. iam back. i have found absolute value for vectors by commanding abs.. now i could not do divide (n1.n2/|n1| |n2|)..

yes.. iam back. i have found absolute values for vectors by commanding abs.. now i could not do divide (n1.n2/|n1| n2)..

Answer 1

[KSSV]

abs gives you +ve value. In your case what you have to use is norm. If I am not mistaken n1 stand for norm/ magnitude of the vector. You have to follow as below:

n1 = rand(1,10) ;
n2 = rand(1,10) ;

iwant = n1*n2'/(norm(n1)*norm(n2))

[Ram kumar Masilamani]

Dear KSSV, I need to find out the dihedral angles .. by following your answer I got (2.22, .2333, 0.322) like these values.. thank you for your quick answer.

[Ram kumar Masilamani]

Iam expecting value like -58.12(for ex) degree ..for this can you help me.. am using theta=cos(-1)(n1.n2/|n1||n2|) formula to find out dihedral values of 2CYU protein..

[KSSV]

That's what the code does....code gives you a single number...whose cos inverse gives you a angle in degrees.

[Jan]

@Ram: It is hard to guess, what you are asking for. Explicit examples would be useful. KSSV's code cannot create an output like "(2.22, .2333, 0.322)", therefore I'm not sure, what this means. Perhaps you want:

Result = acosd((n1 * n2.') / (norm(n1) * norm(n2)))

[Ram kumar Masilamani]

@jan: yeah its very hard to understand me. with your answer, I found the answer as follows. My huge doubt is that it is correct value of psi angle..?please leave a reply.. please x1=[6.630]; y1=[12.294]; z1=[-1.457]; x2=[7.613]; y2=[12.686]; z2=[-0.404]; x3=[8.324]; y3=[11.427]; z3=[0.102]; x4=[9.372]; y4=[11.018]; z4=[-0.564]; v1=[x2-x1, y2-y1, z2-z1]

v1 =

    0.9830    0.3920    1.0530

v2=[x3-x2, y3-y2, z3-z2]

v2 =

    0.7110   -1.2590    0.5060

v3=[x4-x3, y4-y3, z4-z3]

v3 =

    1.0480   -0.4090   -0.6660

n1=cross(v1,v2)

n1 =

    1.5241    0.2513   -1.5163

n2=cross(v2,v3)

n2 =

    1.0454    1.0038    1.0286

x=cos(-1)

x =

    0.5403

y=dot(n1,n2)

y =

    0.2859

y1=(n1*n2.')

y1 =

    0.2859

z=norm(n1).*norm(n2)

z =

    3.8468

ans=x.*(y./z)

ans =

    0.0402