How can I find the Laplace transform of erf without using tables?

janrain
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how do i find the laplace transform of the following error function without using tables?
f(t)=erf(t^(1/2))
i've been trying really long but i seem to be stuck in a loop of erf
 
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janrain said:
how do i find the laplace transform of the following error function without using tables?
f(t)=erf(t^(1/2))
i've been trying really long but i seem to be stuck in a loop of erf

Hey Jarain. Suppose you mean other than Mathematica right?

Just perform the integrations directly then:

\mathcal{L}\left\{\text{Erf}[\sqrt{t}]\right\}=<br /> \int_0^{\infty}e^{-st}\left[\frac{2}{\sqrt{\pi}}\int_0^{\sqrt{t}} e^{-u^2}du\right]dt

Now, can you switch the order of integrations to effect the solution?
 
Last edited:
janrain said:
how do i find the laplace transform of the following error function without using tables?
f(t)=erf(t^(1/2))
i've been trying really long but i seem to be stuck in a loop of erf

Try integrating by parts.
 
Tide said:
Try integrating by parts.

Nice! Thanks.:smile:

Well, then do it both ways Jarain. :rolleyes:

Edit: Oh yea. Tide's way is better.:smile:
 
Hi! I actually just performed this transform recently.
Let dv/dt = \int e^{-st}
Let u = \int_0^{\sqrt{t}} e^{-x^2} dx
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
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