fprintf operates column-wise when given an array as input. So for matrix tmp, fprintf prints tmp(1,1) then tmp(2,1), ..., tmp(end,1), (i.e., down the first column of tmp first), then it starts on the second column and prints tmp(1,2), tmp(2,2), ..., etc., until the last element of tmp.
To print row-wise (across the rows of tmp first), simply pass the transpose of tmp to fprintf.
Example:
range = [1,50;51,100;101,150];
data = rand(150,4)
data =
0.7966 0.5737 0.9403 0.3655
0.3381 0.6147 0.4533 0.4342
0.8237 0.4744 0.7845 0.2163
0.6231 0.8623 0.9023 0.7879
0.9514 0.2122 0.6027 0.5193
0.7194 0.8488 0.3262 0.9797
0.0199 0.6542 0.5303 0.9446
0.4297 0.5473 0.4289 0.5397
0.7277 0.1972 0.0218 0.2461
0.8094 0.6200 0.3109 0.7519
fid = fopen('iris_data.txt', 'a');
tmp = data(range(i,1):range(i,2),:);
fprintf(fid, '%f %f %f %f\n', tmp.');
type('iris_data.txt')
0.796608 0.573716 0.940330 0.365470
0.338104 0.614670 0.453345 0.434154
0.823711 0.474408 0.784532 0.216260
0.623112 0.862271 0.902341 0.787915
0.951388 0.212159 0.602732 0.519335
0.719418 0.848844 0.326197 0.979698
0.019945 0.654194 0.530255 0.944562
0.429711 0.547274 0.428896 0.539668
0.727748 0.197227 0.021791 0.246064
0.809448 0.620045 0.310947 0.751939
0.944291 0.703707 0.983130 0.855440
0.270780 0.251450 0.576403 0.617887
0.728384 0.090845 0.098319 0.241729
0.916850 0.320136 0.160276 0.484155
0.486117 0.574011 0.926226 0.607138
0.206061 0.656239 0.384690 0.010004
0.041487 0.511585 0.002853 0.405765
0.490687 0.308983 0.105843 0.803030
0.896096 0.637228 0.559850 0.238240
0.524963 0.870428 0.674399 0.662380
0.531157 0.859966 0.752705 0.268797
0.139707 0.399779 0.330070 0.481638
0.401618 0.209917 0.783200 0.978098
0.573851 0.331611 0.633014 0.408532
0.498484 0.072790 0.547687 0.728540
0.301108 0.401290 0.785295 0.307191
0.473774 0.639917 0.282754 0.183203
0.157391 0.966926 0.113891 0.851202
0.576856 0.058167 0.125859 0.263212
0.283811 0.173881 0.024041 0.338907
0.140356 0.926013 0.396282 0.718834
0.145473 0.302285 0.698757 0.378406
0.409757 0.646770 0.994155 0.357296
0.571739 0.358293 0.206640 0.268166
0.679702 0.910760 0.765380 0.912009
0.592445 0.342932 0.069698 0.328217
0.362431 0.705796 0.734776 0.321414
0.437603 0.119327 0.471346 0.241670
0.790261 0.640711 0.708852 0.905825
0.402320 0.145556 0.235735 0.822787
0.136766 0.329964 0.400589 0.403540
0.084362 0.736580 0.170749 0.576361
0.021379 0.601187 0.049998 0.134408
0.425733 0.350466 0.055853 0.751774
0.564624 0.686029 0.526219 0.340500
0.907418 0.957768 0.759846 0.846776
0.124290 0.192081 0.456192 0.874086
0.101983 0.251587 0.177020 0.482086
0.366005 0.719736 0.884477 0.869868
0.556679 0.401577 0.586374 0.841304
0.123013 0.224334 0.945291 0.618545
0.412261 0.448144 0.021929 0.776566
0.985201 0.029288 0.061865 0.455467
0.857886 0.239486 0.029346 0.905974
0.702086 0.879903 0.521539 0.491594
0.131677 0.973508 0.043939 0.821011
0.730223 0.490193 0.909894 0.598067
0.638320 0.822729 0.249040 0.816405
0.455368 0.182280 0.082225 0.133857
0.034873 0.301527 0.378305 0.158103
0.564750 0.314699 0.306609 0.412623
0.309590 0.918620 0.449294 0.130875
0.859741 0.820411 0.060647 0.006908
0.602833 0.804656 0.622946 0.887856
0.789280 0.713172 0.409861 0.238551
0.833390 0.345656 0.463614 0.562406
0.797881 0.847440 0.051989 0.136877
0.011070 0.656322 0.457275 0.047316
0.030175 0.204585 0.257313 0.949645
0.211697 0.574699 0.258309 0.030537
0.705389 0.848281 0.565714 0.223707
0.591074 0.478062 0.247536 0.863224
0.671512 0.586856 0.159211 0.201922
0.160713 0.368294 0.324228 0.455373
0.315735 0.117384 0.691708 0.586884
0.060369 0.647993 0.769100 0.227493
0.408869 0.291359 0.880992 0.407734
0.113398 0.644520 0.999623 0.899618
0.946155 0.480697 0.348722 0.672063
0.491806 0.611926 0.363012 0.698214
0.284015 0.989688 0.386993 0.702259
0.650906 0.734116 0.788313 0.004655
0.687626 0.585118 0.658104 0.162832
0.970357 0.057048 0.885198 0.128998
0.531112 0.211469 0.204251 0.856810
0.016828 0.791116 0.593669 0.256362
0.183988 0.725037 0.900499 0.018882
0.523975 0.463391 0.794438 0.018412
0.289736 0.438561 0.976803 0.729039
0.212909 0.960805 0.792400 0.391537
0.777000 0.138231 0.973532 0.500144
0.322849 0.924484 0.482038 0.534699
0.227318 0.898244 0.456992 0.995932
0.974017 0.145341 0.849449 0.300498
0.735993 0.868377 0.442441 0.541764
0.094846 0.788306 0.487865 0.520415
0.323927 0.937206 0.858579 0.717947
0.895458 0.613860 0.141741 0.408906
0.963969 0.554738 0.648748 0.970064
0.636944 0.302853 0.235455 0.629859
0.958735 0.076706 0.167498 0.147297
0.345622 0.412289 0.932157 0.679224
0.743126 0.124293 0.473726 0.217875
0.116781 0.089160 0.621388 0.415791
0.208932 0.707999 0.384320 0.564658
0.676485 0.421048 0.900422 0.895682
0.339849 0.180972 0.050639 0.708099
0.109258 0.704573 0.569295 0.058734
0.339495 0.883416 0.968261 0.684073
0.136482 0.125238 0.038196 0.713792
0.846577 0.972549 0.218706 0.922546
0.803252 0.121695 0.056663 0.973559
0.739073 0.149323 0.514568 0.907587
0.999227 0.623894 0.010685 0.427023
0.320041 0.641142 0.028962 0.649783
0.368586 0.479924 0.949873 0.121117
0.017730 0.112999 0.533435 0.510254
0.231674 0.835553 0.194522 0.535738
0.439716 0.119626 0.283140 0.836066
0.896409 0.419600 0.496166 0.202148
0.299865 0.899659 0.106674 0.874136
0.033319 0.048401 0.416774 0.336375
0.950314 0.179859 0.082519 0.375445
0.556576 0.981310 0.569112 0.528779
0.929488 0.063730 0.400012 0.541144
0.576061 0.453414 0.135129 0.131422
0.725898 0.331034 0.534922 0.786177
0.567849 0.211221 0.547770 0.812435
0.893250 0.010429 0.558922 0.085828
0.769174 0.923923 0.860045 0.331264
0.390422 0.385409 0.914047 0.583558
0.576442 0.404121 0.808610 0.952730
0.511620 0.749383 0.380758 0.798636
0.511679 0.778885 0.499868 0.611774
0.479751 0.992584 0.389100 0.603551
0.258845 0.077586 0.945070 0.505772
0.495853 0.000470 0.272381 0.279269
0.748630 0.874843 0.181476 0.153816
0.532622 0.637021 0.891422 0.064919
0.932057 0.286399 0.175866 0.650066
0.160170 0.707791 0.089662 0.816265
0.818529 0.634330 0.233060 0.621709
0.197126 0.516635 0.149465 0.837872
0.660686 0.673902 0.753458 0.319370
0.570806 0.416311 0.706405 0.637598
0.633351 0.137599 0.860110 0.246850
0.915382 0.638592 0.780752 0.024237
0.058129 0.366230 0.761552 0.774763
0.761576 0.073398 0.082230 0.096986
0.302191 0.972751 0.015593 0.956528
You can see that the contents of the file match the data matrix.
Another thing that may be causing confusion is that you are opening the file in append mode (fopen(_,'a')), in which case the data you fprintf is appended to the end of the file. If that's not what's intended, you may be looking at the beginning of the file and seeing not the values of tmp but instead some irrelevant data that was written previously. If you want to write the file "from scratch" use write mode (fopen(_,'w')).
