Using vector3d arrays

[David Mainprice]

Please be as detailed as possible, explain what you want to do, what kind of data you are using. Attaching simplified code and data is always useful.

a) How  can you preallocate vector3d arrays 

% is there a way to create an array of vector3d zeros

% although this does not seem to work correctly

nn=181

pSH = zeros(nn);

b) How should one correctly assign a vector3d element of array in for loop  where ps1  and  ps2 are  vector3d arrays from MTEX velocity function

for i=1:nn

% angle between SKS_prop_dirn vector and fastest S-wave polarization direction ps1
Z_to_ps11 = angle(SKS_prop_dirn,ps1(i),'antipodal')*180.0/pi
% assign SH polarization parallel or near to plane, angle with plane normal Z > 45 degrees
  if(Z_to_ps11 > 45.0)
    SH(i)=vs1(i);
    pSH(i)=ps1(i);
    SV(i)=vs2(i);
    pSV(i)=ps2(i);
  else
    SH(i)=vs2(i);
    pSH(i)=ps2(i);
    SV(i)=vs1(i);
    pSV(i)=ps1(i);
  end
end 

c) why does pSH_max have dimensions of 181 when I was expecting one vector3d ?

pSH_max = pSH(index_max);

Attached script 

Some of these MTEX constructions are not so obvious to me !

all the best David Mainprice

[Ralf Hielscher]

a) preallocation of vector3d

s = [181 1]; % size of the vector to be preallocated
v = vector3d(zeros(s),zeros(s),zeros(s))

b) I don't see anything wrong in your code. Maybe you can make it faster and more elegant by

% compute all angles
Z_to_ps11 = angle(SKS_prop_dirn,ps1,'antipodal')*180.0/pi;

% assign SH polarization parallel or near to plane, angle with plane normal Z > 45 degrees

ind = Z_to_ps11 > 45.0; 

  

SH(ind)=vs1(ind);

pSH(ind)=ps1(ind);

SV(ind)=vs2(ind);

pSV(ind)=ps2(ind);

  

SH(~ind)=vs2(~ind);

pSH(~ind)=ps2(~ind);

SV(~ind)=vs1(~ind);

pSV(~ind)=ps1(~ind);

c) for me it works correctly.

pSV(1)

gives a single vector