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st: input command, inaccuracy using matrices


From   "Christoph Wunder" <christoph.wunder@sowi.uni-bamberg.de>
To   "statalist hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   st: input command, inaccuracy using matrices
Date   Wed, 5 May 2004 18:34:30 +0200

Hello, 

I entered data by using the INPUT command. After that the variables have
been converted to matrices (MKMAT command). When I look at the output
(MATRIX LIST) I notice some kind of inaccuracy, e.g. the original value of
1.06 is given back as 1.0599999.

I have attached the log-file in order to make the error reproducible for
everybody. As I cannot explain the inaccuracy, I wonder if I use the INPUT
command in a wrong way.

Thank you for your assistance.

Christoph


log-file:

----------------------------------------------------------------------------
---
       log:  d:\docs\inputmat.log
  log type:  text
 opened on:   5 May 2004, 18:28:01

. do "C:\DOKUME~1\ba6sp12\LOKALE~1\Temp\STD000000.tmp"

. * data (manual input)
. input x y

             x          y
  1. 1       2
  2. 1.01    2.01
  3. 1.02    2.02
  4. 1.03    2.03
  5. 1.04    2.04
  6. 1.05    2.05
  7. 1.06    2.06
  8. 1.07    2.07
  9. 1.08    2.08
 10. 1.09    2.09
 11. 1.1     2.1
 12. 1.11    2.11
 13. 1.12    2.12
 14. 1.13    2.13
 15. 1.14    2.14
 16. 1.15    2.15
 17. 1.16    2.16
 18. 1.17    2.17
 19. 1.18    2.18
 20. 1.19    2.19
 21. 1.2     2.2
 22. 1.21    2.21
 23. 1.22    2.22
 24. 1.23    2.23
 25. 1.24    2.24
 26. 1.25    2.25
 27. 1.26    2.26
 28. 1.27    2.27
 29. 1.28    2.28
 30. 1.29    2.29
 31. 1.3     2.3
 32. 1.31    2.31
 33. 1.32    2.32
 34. 1.33    2.33
 35. 1.34    2.34
 36. 1.35    2.35
 37. 1.36    2.36
 38. 1.37    2.37
 39. 1.38    2.38
 40. 1.39    2.39
 41. 1.4     2.4
 42. 1.41    2.41
 43. 1.42    2.42
 44. 1.43    2.43
 45. 1.44    2.44
 46. 1.45    2.45
 47. 1.46    2.46
 48. 1.47    2.47
 49. 1.48    2.48
 50. 1.49    2.49
 51. 1.5     2.5
 52. 1.51    2.51
 53. 1.52    2.52
 54. 1.53    2.53
 55. 1.54    2.54
 56. 1.55    2.55
 57. 1.56    2.56
 58. 1.57    2.57
 59. 1.58    2.58
 60. 1.59    2.59
 61. 1.6     2.6
 62. 1.61    2.61
 63. 1.62    2.62
 64. 1.63    2.63
 65. 1.64    2.64
 66. 1.65    2.65
 67. 1.66    2.66
 68. 1.67    2.67
 69. 1.68    2.68
 70. 1.69    2.69
 71. 1.7     2.7
 72. 1.71    2.71
 73. 1.72    2.72
 74. 1.73    2.73
 75. 1.74    2.74
 76. 1.75    2.75
 77. 1.76    2.76
 78. 1.77    2.77
 79. 1.78    2.78
 80. 1.79    2.79
 81. 1.8     2.8
 82. 1.81    2.81
 83. 1.82    2.82
 84. 1.83    2.83
 85. 1.84    2.84
 86. 1.85    2.85
 87. 1.86    2.86
 88. 1.87    2.87
 89. 1.88    2.88
 90. 1.89    2.89
 91. 1.9     2.9
 92. 1.91    2.91
 93. 1.92    2.92
 94. 1.93    2.93
 95. 1.94    2.94
 96. 1.95    2.95
 97. 1.96    2.96
 98. 1.97    2.97
 99. 1.98    2.98
100. 1.99    2.99
101. 2       3
102. end

. 
. *convert to matrices
. mkmat x y, matrix(a)

. mkmat x, matrix(x)

. mkmat y, matrix(y)

. 
. *operation
. matrix z=y-x

. 
. *view output 
. matrix list a

a[101,2]
              x          y
  r1          1          2
  r2       1.01       2.01
  r3       1.02       2.02
  r4       1.03       2.03
  r5       1.04       2.04
  r6       1.05       2.05
  r7  1.0599999  2.0599999
  r8  1.0700001  2.0699999
  r9       1.08  2.0799999
 r10       1.09  2.0899999
 r11        1.1  2.0999999
 r12       1.11  2.1099999
 r13       1.12  2.1199999
 r14       1.13  2.1300001
 r15       1.14  2.1400001
 r16       1.15  2.1500001
 r17       1.16  2.1600001
 r18       1.17  2.1700001
 r19  1.1799999  2.1800001
 r20  1.1900001  2.1900001
 r21        1.2        2.2
 r22       1.21       2.21
 r23       1.22       2.22
 r24       1.23       2.23
 r25       1.24       2.24
 r26       1.25       2.25
 r27       1.26       2.26
 r28       1.27       2.27
 r29       1.28       2.28
 r30       1.29       2.29
 r31        1.3        2.3
 r32  1.3099999  2.3099999
 r33  1.3200001  2.3199999
 r34       1.33  2.3299999
 r35       1.34  2.3399999
 r36       1.35  2.3499999
 r37       1.36  2.3599999
 r38       1.37  2.3699999
 r39       1.38  2.3800001
 r40       1.39  2.3900001
 r41        1.4  2.4000001
 r42       1.41  2.4100001
 r43       1.42  2.4200001
 r44  1.4299999  2.4300001
 r45  1.4400001  2.4400001
 r46       1.45       2.45
 r47       1.46       2.46
 r48       1.47       2.47
 r49       1.48       2.48
 r50       1.49       2.49
 r51        1.5        2.5
 r52       1.51       2.51
 r53       1.52       2.52
 r54       1.53       2.53
 r55       1.54       2.54
 r56       1.55       2.55
 r57  1.5599999  2.5599999
 r58  1.5700001  2.5699999
 r59       1.58  2.5799999
 r60       1.59  2.5899999
 r61        1.6  2.5999999
 r62       1.61  2.6099999
 r63       1.62  2.6199999
 r64       1.63  2.6300001
 r65       1.64  2.6400001
 r66       1.65  2.6500001
 r67       1.66  2.6600001
 r68       1.67  2.6700001
 r69  1.6799999  2.6800001
 r70  1.6900001  2.6900001
 r71        1.7        2.7
 r72       1.71       2.71
 r73       1.72       2.72
 r74       1.73       2.73
 r75       1.74       2.74
 r76       1.75       2.75
 r77       1.76       2.76
 r78       1.77       2.77
 r79       1.78       2.78
 r80       1.79       2.79
 r81        1.8        2.8
 r82  1.8099999  2.8099999
 r83  1.8200001  2.8199999
 r84       1.83  2.8299999
 r85       1.84  2.8399999
 r86       1.85  2.8499999
 r87       1.86  2.8599999
 r88       1.87  2.8699999
 r89       1.88  2.8800001
 r90       1.89  2.8900001
 r91        1.9  2.9000001
 r92       1.91  2.9100001
 r93       1.92  2.9200001
 r94  1.9299999  2.9300001
 r95  1.9400001  2.9400001
 r96       1.95       2.95
 r97       1.96       2.96
 r98       1.97       2.97
 r99       1.98       2.98
r100       1.99       2.99
r101          2          3

. matrix list z

z[101,1]
              x
  r1          1
  r2          1
  r3          1
  r4          1
  r5          1
  r6          1
  r7          1
  r8  .99999988
  r9  .99999988
 r10  .99999988
 r11  .99999988
 r12  .99999988
 r13  .99999988
 r14  1.0000001
 r15  1.0000001
 r16  1.0000001
 r17  1.0000001
 r18  1.0000001
 r19  1.0000001
 r20          1
 r21          1
 r22          1
 r23          1
 r24          1
 r25          1
 r26          1
 r27          1
 r28          1
 r29          1
 r30          1
 r31          1
 r32          1
 r33  .99999988
 r34  .99999988
 r35  .99999988
 r36  .99999988
 r37  .99999988
 r38  .99999988
 r39  1.0000001
 r40  1.0000001
 r41  1.0000001
 r42  1.0000001
 r43  1.0000001
 r44  1.0000001
 r45          1
 r46          1
 r47          1
 r48          1
 r49          1
 r50          1
 r51          1
 r52          1
 r53          1
 r54          1
 r55          1
 r56          1
 r57          1
 r58  .99999988
 r59  .99999988
 r60  .99999988
 r61  .99999988
 r62  .99999988
 r63  .99999988
 r64  1.0000001
 r65  1.0000001
 r66  1.0000001
 r67  1.0000001
 r68  1.0000001
 r69  1.0000001
 r70          1
 r71          1
 r72          1
 r73          1
 r74          1
 r75          1
 r76          1
 r77          1
 r78          1
 r79          1
 r80          1
 r81          1
 r82          1
 r83  .99999988
 r84  .99999988
 r85  .99999988
 r86  .99999988
 r87  .99999988
 r88  .99999988
 r89  1.0000001
 r90  1.0000001
 r91  1.0000001
 r92  1.0000001
 r93  1.0000001
 r94  1.0000001
 r95          1
 r96          1
 r97          1
 r98          1
 r99          1
r100          1
r101          1

. 
end of do-file

.  log close
       log:  d:\docs\inputmat.log
  log type:  text
 closed on:   5 May 2004, 18:28:28
----------------------------------------------------------------------------
---


Christoph Wunder, Diplom-Volkswirt 
Otto-Friedrich-Universität Bamberg
Professur für VWL, insb. Sozialpolitik 
Feldkirchenstrasse 21
96045 Bamberg Germany
phone: ++49-951-8632601 (2569) 
e-mail: christoph.wunder@sowi.uni-bamberg.de



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