1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
|
subroutine mult2(A,lla,lua, na, nna, B,llb,lub,nb,nnb,C,nc,nnc)
c This subroutine multiplies together two polynomials a(x) and b(x):
c (for multiplying two polynomials, both in F an B)
c Note that la and lb, the dimensions of A and B from the main program
c may be different from that used in the subroutine
c
c a(x) = a(-na)x^(-na) + ...+ a0 + a1*x^(1) + a2*x^(2) + ... + a(nna)*x^(nna)
c
c b(x) = b(-nb)x^(-nb) + ...+ b0 + b1*x^(1) + b2*x^(2) + ... + b(nnb)*x^(nnb)
c
c Note that the general form used here has positive signs for the
c coefficients. The coefficients are stored in elements -na to nna of
c array A and -nb to nnb of array B in the order of increasing powers of x, i.e.
c
c A(-na:na) = [a(-na), ...a0, a1, ... , a(nna)]'.
c
c B(-nb:nb) = [b(-nb), ...b0, b1, ... , b(nnb)]'.
c
c The product c(x) = a(x)b(x), its coefficients are
c stored in the array C = [c0, ... , c(nc)]'.
c Note, nc is the dimensions of the vector c, but all of the vector may not be used
double precision A(-lla:lua),B(-llb:lub),C(-nc:nnc)
do 1 j = -nc,nnc
C(j) = 0.0D0
1 continue
do 3 j = -na,nna
do 4 k = -nb,nnb
C(k+j) = C(k+j) + A(j)*B(k)
4 continue
3 continue
c do 2 i = -(na+nb),nna+nnb
c do 3 j = -na,nna
c do 4 k = -nb,nnb
c if (k+j .eq. i) then
c C(i) = C(i) + A(j)*B(k)
c end if
c4 continue
c3 continue
c2 continue
return
end
|
