## 519 Reputation

14 years, 129 days

Thank you

## Yes, I'm very bad in Maple...

Yes, this storage take little memory. There is no need to work with vectors.

Thank you very much.

## my problem is the storage of big Matrix(...

I have big Matrix(150000,150000) which consume high memory.

I think store the matrix as vectors representing the diagonal and non zero values is good idea.

How to use vectors instead matrix and solve the system for very big matrices

## I have square matrix higher than 150000x...

When I initialize the matrix with Matrix(150000, 150000) and work with it, the consumed memory is very high.

For this, I want to store the matrix as vectors and solve the system. The vectors are corresponding to non zero values and ther positions in row and colon.

Thank you

## How to know the values of A(i) by the co...

Although, how to know the values of A(i) by seeing the different colors of the 3d curve.

Is it possible to get with the plot a bar graphe (or legend) where there are all the colors of the plot with an indication of the values of colors.

Thanks

## Yes A(i) color is good choise as density...

I attached a part of my code. essai.mw

Replacing A with color is a good idea for a plot equivalent to density plot.

## Define a Fourier serie of type "f(x):=a0...

My objective id to define a Fourier serie of type "a0+Sum(an(n)*cos(n*Pi/ln(x2/x1)*ln(x/x1))+ bn(n)*sin(n*Pi/ln(x2/x1)*ln(x/x1)),n=1..N)" in range [x1..x2]

However, int(C(n,x)*S(m,x)/x,x=x1..x2) is not null.

where:

C := (n,x) -> cos(n*Pi*ln(x/x1)/ln(x2/x1));

S := (n,x) -> sin(n*Pi*ln(x/x1)/ln(x2/x1));

I don't know if it's possible to get this type of serie.

Thanks

## My problem is C(n,x)*S(m,x)...

My problem is int(C(n,x)*S(m,x)/x,x=x1..x2) is not null.

## My goal is a basis as...

The basis cos(n*Pi*ln(x)), sin(n*Pi*ln(x)) is orthogonal in the period 1..exp(2)

My goal if possible to get a basis (orthogonal) as

cos(n*Pi/ln(x2/x1)*ln(x/x1)) and sin(n*Pi/ln(x2/x1)*ln(x/x1)) in the range [x1 x2]

Thanks

## Yes, I have the response...

Yes.

Although,

a0+Sum(an*cos(n*Pi*ln(x))+bn*sin(n*Pi*ln(x)),n=1..N) is ok

In the period 1 to exp(2) it is biorthogonal

## Improvement of pdsolve...

Thank you very mach for this post.

I'm looking for more improvement for pdsolve as:

pde[25] with f(x,y) as source and not 0.

pde[23] with f(r,theta) as source and not 0.

and other improvements for Helmoltz equations

Thanks

Thank you

## Tabulate do work...

Yes, Tabulate do a good work

Thank you