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asked 2018-08-08 13:41:12 +0200

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Symbolic Integration works only with second dummy variable

Hi there,

I am trying get an symbolic expression for the convolution $$ (\psi \star f)(x) := \int\limits_{\mathbb{R}} \psi(x-y) f(y) {d y} $$

of two functions $ f, \psi: \mathbb{R} \to \mathbb{R} $ as follows:

var('y') psi = function('psi')(y)
f = function('f')(y)
integrate(psi(x-y)*f(y),y)

upon which I get the error message

RuntimeError: ECL says: Error executing code in Maxima:

If I add an extra argument to the two functions and define them as $$ f, \psi : \mathbb{R} \times \mathbb{R} \to \mathbb{R} $$ as follows:

var('t')
psi = function('psi')(t,y)
f = function('f')(t,y)
integrate(psi(t,x-y)*f(t,y),y)

there is a surprise, it suddenly works! I get the desired symbolic expression on which I can run diff(..,x) and all the other built-in functions.

What is happening here?

Symbolic Integration works only with second dummy variable

Hi there,

I am trying get an symbolic expression for the convolution $$ (\psi \star f)(x) := \int\limits_{\mathbb{R}} \psi(x-y) f(y) {d y} $$

of two functions $ f, \psi: \mathbb{R} \to \mathbb{R} $ as follows:

var('y') var('y')
psi = function('psi')(y)
f = function('f')(y)
integrate(psi(x-y)*f(y),y)

upon which I get the error message

RuntimeError: ECL says: Error executing code in Maxima:

If I add an extra argument to the two functions and define them as $$ f, \psi : \mathbb{R} \times \mathbb{R} \to \mathbb{R} $$ as follows:

var('t')
psi = function('psi')(t,y)
f = function('f')(t,y)
integrate(psi(t,x-y)*f(t,y),y)

there is a surprise, it suddenly works! I get the desired symbolic expression on which I can run diff(..,x) and all the other built-in functions.

What is happening here?am I missing here ?

TL;DR Why does integrate(f(y)*f(y),y) return an error?

Symbolic Integration works only with second dummy variable

TL;DR Why does integrate(f(y)*f(y),y) return an error?

Hi there,

I am trying get an symbolic expression for the convolution $$ (\psi \star f)(x) := \int\limits_{\mathbb{R}} \psi(x-y) f(y) {d y} $$

of two functions $ f, \psi: \mathbb{R} \to \mathbb{R} $ as follows:

var('y')
psi = function('psi')(y)
f = function('f')(y)
integrate(psi(x-y)*f(y),y)

upon which I get the error message

RuntimeError: ECL says: Error executing code in Maxima:

If I add an extra argument to the two functions and define them as $$ f, \psi : \mathbb{R} \times \mathbb{R} \to \mathbb{R} $$ as follows:

var('t')
psi = function('psi')(t,y)
f = function('f')(t,y)
integrate(psi(t,x-y)*f(t,y),y)

there is a surprise, it suddenly works! I get the desired symbolic expression on which I can run diff(..,x) and all the other built-in functions.

What am I missing here ?

TL;DR Why does integrate(f(y)*f(y),y) return an error?

Symbolic Integration works only with second dummy variable

TL;DR Why does integrate(f(y)*f(y),y)integrate(psi(y)*f(y),y) return an error?

Hi there,

I am trying get an symbolic expression for the convolution $$ (\psi \star f)(x) := \int\limits_{\mathbb{R}} \psi(x-y) f(y) {d y} $$

of two functions $ f, \psi: \mathbb{R} \to \mathbb{R} $ as follows:

var('y')
psi = function('psi')(y)
f = function('f')(y)
integrate(psi(x-y)*f(y),y)

upon which I get the error message

RuntimeError: ECL says: Error executing code in Maxima:

If I add an extra argument to the two functions and define them as $$ f, \psi : \mathbb{R} \times \mathbb{R} \to \mathbb{R} $$ as follows:

var('t')
psi = function('psi')(t,y)
f = function('f')(t,y)
integrate(psi(t,x-y)*f(t,y),y)

there is a surprise, it suddenly works! I get the desired symbolic expression on which I can run diff(..,x) and all the other built-in functions.

What am I missing here ?

Symbolic Integration works only with second dummy variable

TL;DR Why does integrate(psi(y)*f(y),y) return an error?

Hi there,

I am trying get an symbolic expression for the convolution $$ (\psi \star f)(x) := \int\limits_{\mathbb{R}} \psi(x-y) f(y) {d y} $$

of two functions $ f, \psi: \mathbb{R} \to \mathbb{R} $ as follows:

var('y')
psi = function('psi')(y)
f = function('f')(y)
integrate(psi(x-y)*f(y),y)

upon which I get the error message

RuntimeError: ECL says: Error executing code in Maxima:

If I add an extra argument to the two functions and define them as $$ f, \psi : \mathbb{R} \times \mathbb{R} \to \mathbb{R} $$ as follows:

var('t')
psi = function('psi')(t,y)
f = function('f')(t,y)
integrate(psi(t,x-y)*f(t,y),y)

there is a surprise, it suddenly works! I get the desired symbolic expression on which I can run diff(..,x) and all the other built-in functions.

What am I missing here ?

Why does integrate(f1(y)*f2(y),y) return an error but integrate(f1(t,y)*f2(t,y),y) works?

Symbolic Integration works only with second dummy variable

TL;DR Why does integrate(psi(y)*f(y),y) return an error?

Hi there,

I am trying get an symbolic expression for the convolution $$ (\psi \star f)(x) := \int\limits_{\mathbb{R}} \psi(x-y) f(y) {d y} $$

of two functions $ f, \psi: \mathbb{R} \to \mathbb{R} $ as follows:

var('y')
psi = function('psi')(y)
f = function('f')(y)
integrate(psi(x-y)*f(y),y)

upon which I get the error message

RuntimeError: ECL says: Error executing code in Maxima:

If I add an extra argument to the two functions and define them as $$ f, \psi : \mathbb{R} \times \mathbb{R} \to \mathbb{R} $$ as follows:

var('t')
psi = function('psi')(t,y)
f = function('f')(t,y)
integrate(psi(t,x-y)*f(t,y),y)

there is a surprise, it suddenly works! I get the desired symbolic expression on which I can run diff(..,x) and all the other built-in functions.

TL;DR Why does integrate(psi(y)*f(y),y) return an error?

What am I missing here ?

Why does integrate(f1(y)*f2(y),y) return an error but integrate(f1(t,y)*f2(t,y),y) works?

Symbolic Integration works only with second dummy variable

Hi there,

I am trying get an symbolic expression for the convolution $$ (\psi \star f)(x) := \int\limits_{\mathbb{R}} \psi(x-y) f(y) {d y} $$

of two functions $ f, \psi: \mathbb{R} \to \mathbb{R} $ as follows:

var('y')
psi = function('psi')(y)
f = function('f')(y)
integrate(psi(x-y)*f(y),y)

upon which I get the error message

RuntimeError: ECL says: Error executing code in Maxima:

If I add an extra argument to the two functions and define them as $$ f, \psi : \mathbb{R} \times \mathbb{R} \to \mathbb{R} $$ as follows:

var('t')
psi = function('psi')(t,y)
f = function('f')(t,y)
integrate(psi(t,x-y)*f(t,y),y)

there is a surprise, it suddenly works! I get the desired symbolic expression on which I can run diff(..,x) and all the other built-in functions.

TL;DR Why does integrate(psi(y)*f(y),y) return an error?

What am I missing here ?

Why does integrate(f1(y)*f2(y),y) integrate(psi(y)*f(y),y) return an error but integrate(f1(t,y)*f2(t,y),y) integrate(psi(t,y)*f(t,y),y) works?

Symbolic Integration works only with second dummy variable

Hi there,

I am trying get an symbolic expression for the convolution $$ (\psi \star f)(x) := \int\limits_{\mathbb{R}} \psi(x-y) f(y) {d y} $$

of two functions $ f, \psi: \mathbb{R} \to \mathbb{R} $ as follows:

var('y')
psi = function('psi')(y)
f = function('f')(y)
integrate(psi(x-y)*f(y),y)

upon which I get the error message

RuntimeError: ECL says: Error executing code in Maxima:

If I add an extra argument to the two functions and define them as $$ f, \psi : \mathbb{R} \times \mathbb{R} \to \mathbb{R} $$ as follows:

var('t')
psi = function('psi')(t,y)
f = function('f')(t,y)
integrate(psi(t,x-y)*f(t,y),y)

there is a surprise, it suddenly works! I get the desired symbolic expression on which I can run diff(..,x) and all the other built-in functions.

TL;DR Why does integrate(psi(y)*f(y),y) return an error?

What am I missing here ?

Solved: Why does integrate(psi(y)*f(y),y) return an error but integrate(psi(t,y)*f(t,y),y) works?

Symbolic Integration works only with second dummy variable

Hi there,

I am trying get an symbolic expression for the convolution $$ (\psi \star f)(x) := \int\limits_{\mathbb{R}} \psi(x-y) f(y) {d y} $$

of two functions $ f, \psi: \mathbb{R} \to \mathbb{R} $ as follows:

var('y')
psi = function('psi')(y)
f = function('f')(y)
integrate(psi(x-y)*f(y),y)

upon which I get the error message

RuntimeError: ECL says: Error executing code in Maxima:

If I add an extra argument to the two functions and define them as $$ f, \psi : \mathbb{R} \times \mathbb{R} \to \mathbb{R} $$ as follows:

var('t')
psi = function('psi')(t,y)
f = function('f')(t,y)
integrate(psi(t,x-y)*f(t,y),y)

there is a surprise, it suddenly works! I get the desired symbolic expression on which I can run diff(..,x) and all the other built-in functions.

TL;DR Why does integrate(psi(y)*f(y),y) return an error?

What am I missing here ?Solution Use sympy backend for symbolic integration as in integrate(psi(x-y)*f(y),y, algorithm="sympy")

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