## 175 Reputation

15 years, 71 days

## @Markiyan Hirnyk Thanks again. Let ...

@Markiyan Hirnyk Thanks again. Let me explain my equation more. My equation has the exact form:

> eq := z->H*(1-m*H(0)^2*(1+z)^3/H^2)-2*e*sqrt(1-c^2)*sqrt(r)*H(0) = 0;

and from some observational and physical reasons I'd like to replace H(0) by h=0.741. I think you are going to tell me this initial condition is wrong and the physical H(0) I'm looking for is Y(0). O.K., then, how can I solve this equation? i,e, what should I insert in my equation instead of H(0)?

## @Markiyan Hirnyk Thanks again. Let ...

@Markiyan Hirnyk Thanks again. Let me explain my equation more. My equation has the exact form:

> eq := z->H*(1-m*H(0)^2*(1+z)^3/H^2)-2*e*sqrt(1-c^2)*sqrt(r)*H(0) = 0;

and from some observational and physical reasons I'd like to replace H(0) by h=0.741. I think you are going to tell me this initial condition is wrong and the physical H(0) I'm looking for is Y(0). O.K., then, how can I solve this equation? i,e, what should I insert in my equation instead of H(0)?

Thanks for your reply. From what you wrote it seems to me that Y(z) should be the same as H(z). Because that's the root of equation in H(z). Am I right? Then, why Y(0) differs from H(0) or h?

Thanks for your reply. From what you wrote it seems to me that Y(z) should be the same as H(z). Because that's the root of equation in H(z). Am I right? Then, why Y(0) differs from H(0) or h?

@acer Thanks for your reply. That's very nice. But your notation does not work in general. My data are not results of DEs. They ontain from a chi squared method (a statistical approach to best fit some model parameters) to plot some confidence region. I have too much data and I can pointplot all of them and obtain a beautiful plot, but I want to plot only the edge of this area. I sent you a very short data. If I add some of the others data to each list I obtain very bad plot. For example if I change ch1 to

> ch1 := [[0.5e-2, -.57], [0.1e-1, -.56], [0.25e-1, -.57], [0.35e-1, -.555], [0.8e-1, -.485], [0.9e-1, -.42], [.115, -.43], [.125, -.36], [.155, -.365], [.16, -.3], [.17, -.34], [.175, -.275], [.195, -.24], [.23, -.24], [.23, -.18], [.245, -.215], [.25, -.145], [.275, -.1], [.28, -.155], [.3, -.12], [.31, -0.35e-1], [.315, -0.25e-1], [.32, -0.85e-1], [.345, -0.4e-1], [.355, 0.55e-1], [.36, 0.65e-1], [.375, 0.15e-1], [.38, .11], [.39, .135], [.405, .175], [.41, .19], [.415, .205], [.425, .11], [.425, .24], [.425, .425], [.425, .43], [.425, .435], [.425, .44], [.43, .12], [.43, .265], [.43, .405], [.43, .41], [.43, .44], [.43, .445], [.435, .295], [.435, .38], [.435, .385], [.435, .445], [.44, .445], [.445, .445], [.45, .445], [.465, .195], [.465, .44], [.48, .43], [.485, .245], [.485, .425], [.49, .42], [.5, .29], [.5, .405], [.505, .31], [.505, .395], [.51, .345], [.51, .35], [.51, .355], [.51, .36], [.51, .365], [.51, .37]];

> ch11 := simplex[convexhull](ch1,output=[hull]):

> ch1b:={op(ch1)} minus {op(ch11)}:

> ch1b1:=simplex[convexhull](ch1b,output=[hull]):

> ch01 := plot( [op(ch11), op(ListTools:-Reverse(ch1b1))] ):

> display(ch01);

Regards.

@acer Thanks for your reply. That's very nice. But your notation does not work in general. My data are not results of DEs. They ontain from a chi squared method (a statistical approach to best fit some model parameters) to plot some confidence region. I have too much data and I can pointplot all of them and obtain a beautiful plot, but I want to plot only the edge of this area. I sent you a very short data. If I add some of the others data to each list I obtain very bad plot. For example if I change ch1 to

> ch1 := [[0.5e-2, -.57], [0.1e-1, -.56], [0.25e-1, -.57], [0.35e-1, -.555], [0.8e-1, -.485], [0.9e-1, -.42], [.115, -.43], [.125, -.36], [.155, -.365], [.16, -.3], [.17, -.34], [.175, -.275], [.195, -.24], [.23, -.24], [.23, -.18], [.245, -.215], [.25, -.145], [.275, -.1], [.28, -.155], [.3, -.12], [.31, -0.35e-1], [.315, -0.25e-1], [.32, -0.85e-1], [.345, -0.4e-1], [.355, 0.55e-1], [.36, 0.65e-1], [.375, 0.15e-1], [.38, .11], [.39, .135], [.405, .175], [.41, .19], [.415, .205], [.425, .11], [.425, .24], [.425, .425], [.425, .43], [.425, .435], [.425, .44], [.43, .12], [.43, .265], [.43, .405], [.43, .41], [.43, .44], [.43, .445], [.435, .295], [.435, .38], [.435, .385], [.435, .445], [.44, .445], [.445, .445], [.45, .445], [.465, .195], [.465, .44], [.48, .43], [.485, .245], [.485, .425], [.49, .42], [.5, .29], [.5, .405], [.505, .31], [.505, .395], [.51, .345], [.51, .35], [.51, .355], [.51, .36], [.51, .365], [.51, .37]];

> ch11 := simplex[convexhull](ch1,output=[hull]):

> ch1b:={op(ch1)} minus {op(ch11)}:

> ch1b1:=simplex[convexhull](ch1b,output=[hull]):

> ch01 := plot( [op(ch11), op(ListTools:-Reverse(ch1b1))] ):

> display(ch01);

Regards.

## Hello! Is my question difficult? If mapl...

Hello! Is my question difficult? If maple can't give me what I want, please tell me. Thanks.

## Thanks. Do you think that I can solve th...

Thanks. Do you think that I can solve this system in a different way?

## Thanks. Do you think that I can solve th...

Thanks. Do you think that I can solve this system in a different way?

## @Markiyan Hirnyk I don't understand...

@Markiyan Hirnyk I don't understand what you mean. Would you explain it more please?

## @Markiyan Hirnyk I don't understand...

@Markiyan Hirnyk I don't understand what you mean. Would you explain it more please?

## @Markiyan Hirnyk I added these line...

@Markiyan Hirnyk I added these lines to my worksheet:

> sol(parameters);

> sol(parameters = [0.63, 0.1]);

but after the last I get an error:

Error, (in f) unable to store '-HFloat(1.587301587301588)*(D(H))(0)*(D(psi))(0)+HFloat(2.000000000000001)*(D(psi))(0)-HFloat(1.0807245940629369e-4)' when datatype=float[8]

What can I do to solve this problem? Thanks again.

## @Markiyan Hirnyk I added these line...

@Markiyan Hirnyk I added these lines to my worksheet:

> sol(parameters);

> sol(parameters = [0.63, 0.1]);

but after the last I get an error:

Error, (in f) unable to store '-HFloat(1.587301587301588)*(D(H))(0)*(D(psi))(0)+HFloat(2.000000000000001)*(D(psi))(0)-HFloat(1.0807245940629369e-4)' when datatype=float[8]

What can I do to solve this problem? Thanks again.

## @Markiyan Hirnyk Thank you so much....

@Markiyan Hirnyk Thank you so much. Can you tell me please where should I identify the values of "a" and "b"? I entered their values after "sol := ......". Am I right?

My another question is how can I calculate the value of H in a special z. For example: H(0.5)

## @Markiyan Hirnyk Thank you so much....

@Markiyan Hirnyk Thank you so much. Can you tell me please where should I identify the values of "a" and "b"? I entered their values after "sol := ......". Am I right?

My another question is how can I calculate the value of H in a special z. For example: H(0.5)

 3 4 5 6 7 8 9 Page 5 of 12
﻿