Hi,

I have these lines in my code, the function alpha:=(m,n,1)->...... is defined in the last line of the code below, but when I want to calculate alpah(1,1,1), there is no numeric value. Why???? Many thinks

restart:

with(LinearAlgebra):

with(plots):

with(PDEtools):

with(IntegrationTools):

interface(rtablesize=20):

d:=1: N:=2: a:=1: h:=a/N:

Kernel(x,y):=ln(abs(x-y)):

eq2:=int(Kernel(x,y)*phi(y),y=-a..a)=sum(int(Kernel(x,y)*phi(y),y=n*h..(n+d)*h),n=-N..N-d):

Approximate the integral

eq3:=phi->int(Kernel(x,y)*phi(y),y=n*h..(n+d)*h)=add(beta[i,n]*phi((n+i-1)*h),i=1..d+1):

eq4:=int(Kernel(x,y)*phi(y),y=n*h..(n+d)*h)=add(alpha[m,n,i]*phi((n+i-1)*h),i=1..d+1):

Compute the coefficients beta[i]

Vct_basis:=[seq(x^i,i=0..d+1)]:

fct:=[seq(unapply(Vct_basis[i],x),i=1..d+2)]:

sys:=[seq(eq3(fct[i]),i=1..d+1)]:

x:=m*h:

w := [seq(beta[i,n],i=1..d+1)]:

M,b := GenerateMatrix(sys,w):

M1:=-M: V:=-b:

Vect_beta:=(M1)^(-1).V:# Vect_beta is a vector.

beta[1]:=Vect_beta[1]:

alpha1:=(n,m)->beta[1];

(n, m) -> beta[1]

alpaha(1,1);

alpaha(1, 1) ??????????????????? No numeric result