9 replies to this topic

[Satoshi]

​I wanted to graph gamma function (integral from 0 to infinity, but 0 to 100 is still accurate, of t^(X-1)*e^-t dt), but i cannot do 'dt', only 'dx', and when I use dx, the program do not know what is the part of integral, and what is the argument of  function.

[piu58]

You have to use x for the integration variable and rewrite the function in x: x^(Z-1)*e^-x dx

[Satoshi]

You have to use x for the integration variable and rewrite the function in x: x^(Z-1)*e^-x dx

 

Z is treated as a variable, not as an argument of a function. Is there a way to set up Z as an argument?

[piu58]

You cannot have x AND z als Argument.

[Satoshi]

You cannot have x AND z als Argument.

So what do i have to do to set only Z as an argument, so it no longer will be treated as a number (stored in variable Z)
So what do i have to do to set only Z as an argument, so it no longer will be treated as a number (stored in variable Z)

[piu58]

I don't know whether we speak about the same thing, but I wrote a program for calculation of the gamma function

Goto I
Lbl A
?->Z
0->S:1->P
For 0->N To 6
S+List 1[N+1]Z^N->S
P(Z+N)->P
Next
(S/P)((Z+5.5)^(Z+.5)e^(-(Z+5.5))
Stop
Lbl I
7->Dim List 1
75122.6331530->List 1[1]
80916.6278952->List 1[2]
36308.2951477->List 1[3]
8687.24529705->List 1[4]
1168.92649479->List 1[5]
83.8676043424->List 1[6]
2.50662827511->List 1[7]
Goto A

[piu58]

The integral gives you a result for  a single value of z. If you want to have a graph of all z, you need to solve the integral for every z independently. Or you use the approach I gave. 

[piu58]

I compared my program with the implemented intergal function. Some examples:

My program :

Z=0.5 G(Z)=1.772453851

Z=2.7 G(Z)=1.544685846

Z=4.1 G(Z)= 6.812622863

 

In Math Mode

999
´
|    Z-1  -X
| X      e    dx
|
,
0

0.5 G(Z)=1.772453679 (runs around 5 seconds)

2.7 G(Z)=1.544685843

4.1 G(Z)=6.812622865

[Satoshi]

I just want to know how to graph of a function with integral in it. Not only the gamma function. But how can i put an argument in the integral if it cannot be X

[piu58]

No way. You may use my litttle program, make loop in Z around it end a plot line in it.