./splinesurv/src/init.c

1. CsplineUtils/cevalCinte2

CsplineUtils/cevalCinte2 [ Functions ]

NAME

    cevalCinte2 --- compute partial integrals of B-spline basis functions

FUNCTION

This is needed to compute the cumulative baseline hazard. This function updates the i-th row of the input matrix cinte, from jstart to jstop, so that cinte[i,j] contains the integral of the j-th B-spline basis function of order ord, defined on the given knots, from 0 to x[i].

SYNOPSIS

263 void cevalCinte2(double *cinte, double *x, int nx, double *knots, int nj, int ord, double *binte,
264         int i, int jstart, int jstop)

INPUTS

    cinte     output matrix of dimension nx x nj
    x         vector of observations at which to evaluate
    nx        length of x
    knots     vector of knot positions, length nj+ord
    ord       order of the spline
    binte     vector of integrals of each B-spline basis function, see cevalBinte
    i         row of cinte to update
    jstart    starting column of cinte to update
    jstop     ending column of cinte to update

SOURCE

268 {
269     int nk = nj + ord;
270     double * knots2 = (double *) malloc((nk +2) * sizeof(double));
271     knots2[0]=knots[0];
272     for(int j=0; j<nk; j++) knots2[j+1]=knots[j];
273     knots2[nk+1]=knots[nk-1];
274     int ord2 = ord+1;
275     double * bs2 = (double *) malloc((nj+1)*  sizeof(double));
276     // compute a basis of order ord+1
277     for(int j=jstart;j<nj+1;j++) bs2[j] = csplineeval(x[i],j,ord2,knots2,ord2,nj);
278     // compute as in evalCinte for the row and set of columns given
279     for(int j=jstart; j<jstop; j++){
280         cinte[i+j* nx]=0;
281         if(x[i]>=knots[j+ord]) cinte[i + j*nx] = binte[j];
282         if((x[i]<knots[j+ord]) & (x[i]>=knots[j]))
283         {
284             for(int k=j+1;k<nj+1;k++) 
285                 cinte[i + j*nx]+=binte[j]*bs2[k];
286         }
287     }
288     free(bs2);
289     free(knots2);
290 
291 }

TABLE OF CONTENTS

CsplineUtils/cevalCinte2 [ Functions ]