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plurals

POLabel used but not defined
primarykey
Id
20454159
data
AcceptedAnswerId
20454267
AnswerCount
2
ClosedDate
CommentCount
7
CommunityOwnedDate
CreationDate
2013-12-08T13:49:54.087
FavoriteCount
0
LastActivityDate
2013-12-08T14:25:21.253
LastEditDate
2013-12-08T13:53:56.817
LastEditorUserId
1629262
OwnerUserId
3058337
ParentId
0
PostTypeId
1
Score
1
ViewCount
3389
LastEditorDisplayName
text
Body
<p>I am trying to solve a linear systems of equations using LU decomposition followed by back substitution. However, in compiling it there is a problem, that states:</p> <pre><code>87:2: error: label ‘a’ used but not defined </code></pre> <p>Do you know what it means? Here is my program: </p> <pre><code>#include <stdio.h> #include <math.h> #include "nrutil.h" #include <stdlib.h> #define TINY 1.0e-20; void ludcmp(float **a, int n, int *indx, float *d) { int i,imax,j,k; float big,dum,sum,temp; float *vv; vv=vector(1,n); *d=1.0; for (i=1;i<=n;i++) { big=0.0; for (j=1;j<=n;j++) if ((temp=fabs(a[i][j])) > big) big=temp; if (big == 0.0) nrerror("Singular matrix in routine ludcmp"); vv[i]=1.0/big; } for (j=1;j<=n;j++) { for (i=1;i<j;i++) { sum=a[i][j]; for (k=1;k<i;k++) sum -= a[i][k]*a[k][j]; a[i][j]=sum; } big=0.0; for (i=j;i<=n;i++) { sum=a[i][j]; for (k=1;k<j;k++) sum -= a[i][k]*a[k][j]; a[i][j]=sum; if ( (dum=vv[i]*fabs(sum)) >= big) { big=dum; imax=i; } } if (j != imax) { for (k=1;k<=n;k++) { dum=a[imax][k]; a[imax][k]=a[j][k]; a[j][k]=dum; } *d = -(*d); vv[imax]=vv[j]; } indx[j]=imax; if (a[j][j] == 0.0) a[j][j]=TINY; if (j != n) { dum=1.0/(a[j][j]); for (i=j+1;i<=n;i++) a[i][j] *= dum; } } free_vector(vv,1,n); } #undef TINY void lubksb(float **a, int n, int *indx, float b[]) { int i,ii=0,ip,j; float sum; for (i=1;i<=n;i++) { ip=indx[i]; sum=b[ip]; b[ip]=b[i]; if (ii) for (j=ii;j<=i-1;j++) sum -= a[i][j]*b[j]; else if (sum) ii=i; b[i]=sum; } for (i=n;i>=1;i--) { sum=b[i]; for (j=i+1;j<=n;j++) sum -= a[i][j]*b[j]; b[i]=sum/a[i][i]; } } int main(){ float a[3][3], c[3][3], b[3], d; int indx[3], i, j; a[1][1]=1.00; a[1][2]=0.80; a[1][3]=0.64; a[2][1]=1.00; a[2][2]=0.90; a[2][3]=0.81; a[3][1]=1.00; a[3][2]=1.10; a[3][3]=1.11; b[0]=erf(0.80); b[1]=erf(0.90); b[2]=erf(1.10); ludcmp(&&a, 3, indx, &d); lubksb(&&a, 3, indx, b); for (i=0; i<=3; i++) printf("%f", b[i]); return 0; } </code></pre>
Tags
<c>
Title
Label used but not defined
singulars
PostAcceptedAnswerId
1. PO
  singulars
  PostTypePostTypeId
  PTAnswer
PostParentId
1. This table or related slice is empty.
PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. USdoptimusprime
UserOwnerUserId
1. USTheDorkSide
plurals
PostLinksPostIdRelatedPostId
1. PL
  singulars
  LinkTypeLinkTypeId
  LTLinked
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. PO
  singulars
  PostTypePostTypeId
  PTAnswer
2. PO
  singulars
  PostTypePostTypeId
  PTAnswer
VotesPostIdCreationDate
1. VO
  singulars
  PostPostId
  POLabel used but not defined
  UserUserId
  This table or related slice is empty.
  VoteTypeVoteTypeId
  VTUpMod
CommentsPostId

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