can anyone expalin num2str in the following script and what is the script doing

count = 1;
j = 1;
%write the parameter section
while(count <= (max_xy-1))
st1 = ['110,' num2str(x(count),'%6.5f') ',' num2str(y(count),'%6.5f') ',' num2str(z(count),'%6.5f') ',' num2str(x(count+1),'%6.5f') ',' num2str(y(count+1),'%6.5f') ',' num2str(z(count+1),'%6.5f') ',' '0,0;']; 
st1 = [st1 blanks(64-length(st1)) numstr(j,' ') numstr(count,'P')];
fprintf(fidw,[st1 '\n']);
count = count + 1;
j = j + 2;
end;
ip = max_xy-1;

Thanks in advance. numstr is a function

function st = numstr(k,ss)
temp_s = length(num2str(k));
tl = 8;
i = 1;
while(i <= (tl-temp_s-1))
    st(i) = ' ';
    i = i + 1;
end;
st = [ss st num2str(k)];

[Jan]

Are you asking for "numstr" or "num2str"? To find out, what the one or the other function is doing, you can simply run them from the command line and see, how the outputs depend on the inputs.

Answer 1

[dpb]

numstr is inserting blanks length 8-length(theStringRepresentationOf the value k passed it). The loop could be replaced by a call to blanks and the function replaced by one of about three lines or so. The end result appears to be a fixed-length string from the concatenation of ss and the value of k with blanks inserted.

The function could also be replaced w/ a single sprintf call.

The whole thing is an extremely convoluted section of code writing a particularly-formatted .csv file. For example, the string st1 that is being built from a half-dozen individual terms can be replaced with

fmt=['110,' repmat('%6.5f,',1,6) '0.0'];
i1=count;i2=i1+1;
st1=sprintf(fmt,[x(i1:i2),y(i1:i2),z(i1:i2)].');

The concatenation of the subsequent pieces could also be replaced with proper formattting.

As Jan suggests, look at a sample of the output file created and just build the format strings required to create that output format. It should be only a couple of lines at most.

doc fprintf

and follow the links to the formatSpec info for the gory details.

The whole loop could be replaced by a judicious reshape and concatenation it would seem.

Answer 2

[dpb]

As mentioned above, the whole piece of code can be turned into a single output statement...

I created a sample set of data as

>> x=rand(10,1)*10; y=rand(10,1)*10; z=rand(10,1)*10;

and put the posted code in a file rsch.m as a function passed the three vectors and echoed the output to the screen getting...

>> rsch(x,y,z)
110,8.40717,7.51267,3.51660,2.54282,2.55095,8.30829,0,0;               1P      1
110,2.54282,2.55095,8.30829,8.14285,5.05957,5.85264,0,0;               3P      2
110,8.14285,5.05957,5.85264,2.43525,6.99077,5.49724,0,0;               5P      3
110,2.43525,6.99077,5.49724,9.29264,8.90903,9.17194,0,0;               7P      4
110,9.29264,8.90903,9.17194,3.49984,9.59291,2.85839,0,0;               9P      5
110,3.49984,9.59291,2.85839,1.96595,5.47216,7.57200,0,0;              11P      6
110,1.96595,5.47216,7.57200,2.51084,1.38624,7.53729,0,0;              13P      7
110,2.51084,1.38624,7.53729,6.16045,1.49294,3.80446,0,0;              15P      8
110,6.16045,1.49294,3.80446,4.73289,2.57508,5.67822,0,0;              17P      9

>> nr=size(x,1)-1;
>> fmt=['110,' repmat('%6.5f,',1,6) '0.0;%16dP%7d\n'];
>> fprintf(fmt,[x(1:nr)  y(1:nr)  z(1:nr) ...
                x(2:end) y(2:end) z(2:end) ...
                [1:2:2*nr].' [1:nr].'].')

110,8.40717,7.51267,3.51660,2.54282,2.55095,8.30829,0.0;               1P      1
110,2.54282,2.55095,8.30829,8.14285,5.05957,5.85264,0.0;               3P      2
110,8.14285,5.05957,5.85264,2.43525,6.99077,5.49724,0.0;               5P      3
110,2.43525,6.99077,5.49724,9.29264,8.90903,9.17194,0.0;               7P      4
110,9.29264,8.90903,9.17194,3.49984,9.59291,2.85839,0.0;               9P      5
110,3.49984,9.59291,2.85839,1.96595,5.47216,7.57200,0.0;              11P      6
110,1.96595,5.47216,7.57200,2.51084,1.38624,7.53729,0.0;              13P      7
110,2.51084,1.38624,7.53729,6.16045,1.49294,3.80446,0.0;              15P      8
110,6.16045,1.49294,3.80446,4.73289,2.57508,5.67822,0.0;              17P      9

And, lo! and behold, the results are the same...