[Scilab-users] For loop - maximum size

[Tingsten]

First, I have just realized that my first post was wrong (cause the final
matrix is not the same). This is better :

1)timer();A=[];for i=1:100000,A=[A;i];,end;timer()
 ans  =
     16.489306  
 
2)timer();B=[];for j=1:10,A=[];for
i=1:10000,A=[A;i];,end;B=[B;A+(j-1)*10000];,end;timer()
 ans  =
     1.0452067  
 
3)timer();B=[];for j=1:100,A=[];for
i=1:1000,A=[A;i];,end;B=[B;A+(j-1)*1000];,end;timer()
 ans  =
     0.4368028 


So same conclusion!

In this case, splitting the for loop does not work well....

-->timer();A=zeros(1,100000);for i=1:100000,A(i)=i;end;timer()
 ans  =
 
    0.4368028  
 
-->timer();B=[];for j=1:100,A=zeros(1,1000);for i=1:1000,A(i)=i;end;,B=[B
A+(j-1)*1000];,end;timer()
 ans  =
 
    0.4212027  

However this loop is an example to illustrate. In my case here are the kind
of loop I use
1)A=mopen('myfile.txt');
X=[];Y=[];Z=[];
winH=waitbar('Coffee break');
for i=1:1000000,
                      B=mgetl(-1,A);
                      [n,x,y,z]=msscanf(1,B,'%*s %*d:%*d:%*f,%d,%d,%d');
                      X=[X;x];Y=[Y;y];Z=[Z;z];
waitbar(j/1000000,winH);
,end;

=>30minutes (I guess cause it's so long that I stopped the loop)


2)A=mopen('myfile.txt');
X=[];Y=[];Z=[];
winH=waitbar('Coffee break');
for j=1:100,
               X2=[];Y2=[];Z2=[];
               for i=1:10000,
                                 B=mgetl(-1,A);
                                 [n,x,y,z]=msscanf(1,B,'%*s
%*d:%*d:%*f,%d,%d,%d');
                                  X2=[X2;x];Y2=[Y2;y];
                ,end;
               Z2=[Z2;z];X=[X;X2];Y=[Y;Y2];Z=[Z;Z2];
               waitbar(j/100,winH);
,end;

=>1 minutes



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