1. WARNING !!
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Included is a matrix multiplication prog that I wrote as part of my Maths
revision. I am sure this has been done many times before, but in case you want
it, here it is.
Use it like this :
eg
[ 1 2 3 ] [ 9 ]
[ 4 5 6 ] x [ 6 ]
[ 7 8 9 ] [ 3 ]
include matrix.e
sequence result
result=matimult( {{1,2,3},{4,5,6},{7,8,9}} , {{9,6,3}} )
NB even for a one-column matrix you still need two sets of {}s
--------- Start of Code (matrix.e)
type matrix(sequence m)
atom r,aleng
sequence len,temp
r=1
len={}
if sequence(m) then
for a=1 to length(m) do
if not sequence(m[a]) then
r=0
exit
else
temp=m[a]
aleng=length(temp)
len=len&aleng
for b=1 to aleng do
if sequence(temp[b]) then
r=0
exit
end if
end for
end if
if r=0 then
exit
end if
end for
else r=0
end if
return r
end type
function matimult(matrix m1,matrix m2)
sequence r
atom this
this=0
if not(length(m1[1])=length(m2)) then
r={0} --If not multiplyable return {0}
else
r=repeat(repeat(0,length(m2[1])),length(m1))
for a=1 to length(m2[1]) do --no. columns in m2
for b=1 to length(m1) do --no. rows in m1
for c=1 to length(m1[1]) do --no. columns in m1
this=this+(m1[b][c]*m2[c][a])
end for
r[b][a]=this
this=0
end for
end for
end if
return r
end function
------End of Code
Code written by D. Johnson rewrite and distribute as you please. Please give
me credit if used in any product.
Daniel Johnson, Les Mailles Telesoft, Coventry, England
