## 328 Reputation

15 years, 200 days

## Fourier transform of a non-integrable fu...

Maple
Fourier transform of a non-integrable function ... Dear all, I am working on Fourier Transform of a non-integrable function. And I am working on the numerical implementation of the FT, using FFT. Let's call this function F(v). One example is F(v)=-1/(5*i*v)*(1-exp(5*i*v)) The function has a 1/v term in its asymptotic expansion, which corresponds to a jump or Heaviside function in its transform. Using FFT, I can see the jump, with some overshooting after the jump and undershooting before the jump, along with some ripples. I want to reduce these artifacts as much as possible, because I am going to integrate this transform against other functions later. Hence obtaining a smooth function without much numerical artifacts is vital. How do I do that?

## Is this thing called Interval Math? Can ...

Maple
Is this thing called Interval Math? Can Maple do it? Is this thing called Interval Math? Can Maple do it? I am not about if this is called Interval Analysis. The thing in my mind is that I know my Monte Carlo simulation yields a result with an error tolerance of 1e-5. And I wrap that MC simulation component into a more complicated expression and form a function, I want to know the error bound of the whole function involving the MC component. Can Maple do this? The same applies to analysis about round-off error. If I know a sub-expression has a round-off error of 1e-6, what should the error of the main expression involving this sub-expression be?

## What's the use of code generator?...

Maple
For trivial expressions, we don't need automatic code generation. For complicated expressions, code generator creates lots of temporary variables and the performance is not far from optimal. Once I generated a C program using codegen with 500+ temporary variables and I put that function into a numerical integral as an integrand. The result was very unstable - the integrals are often NaNs. On the other hand, I also convert Maple expression manually into C program which has exactly the same functionality. The result was correct, no NaNs in the integrals at all. So what's the use o

## How do I programmatically save the outpu...

Maple
How do I programmatically save the output of "C" code generation to a "cpp" file? I am doing all of these in Matlab via the Maple engine, which is version 10, I guess. I cannot seem to do "writeto" redirection here, because Matlab doesn't allow that I guess. And I like to use "fprintf" because it gives me more control of the code that is generated... If it works, I no longer need copy and paste.. But it didn't work at all. There was no error message, but the file was empty... Can anybody tell me why? Thanks! -------------------- fd:=fopen("trygenC.cpp", WRITE, TEXT)

## What's wrong with this codegen with 2D a...

Maple
bb:=proc(aa, n) add(add(aa[j][k], j=0 .. 5), k=0 .. n) end proc cc:=prep2trans(bb) dd:=C(cc, optimized) ??? Error using ==> maple at 129 Error, (in codegen/C) Unable to translate this subscript into C aa[i2][i1] -------------- I don't understand...
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