不完全cholesky分解实现

integer function isamax(n,sx,incx) c

c finds the index of element having max. absolute value. c jack dongarra, linpack, 3/11/78. c

real sx(1),smax integer i,incx,ix,n c

isamax = 0

if( n .lt. 1 ) return isamax = 1

if(n.eq.1)return

if(incx.eq.1)go to 20 c

c code for increment not equal to 1 c

ix = 1

smax = abs(sx(1)) ix = ix + incx do 10 i = 2,n

if(abs(sx(ix)).le.smax) go to 5 isamax = i

smax = abs(sx(ix)) 5 ix = ix + incx 10 continue return c

c code for increment equal to 1 c

20 smax = abs(sx(1)) do 30 i = 2,n

if(abs(sx(i)).le.smax) go to 30 isamax = i

smax = abs(sx(i)) 30 continue return end