@ 

thank you sooo much for your comprehensive answer..

@Carl Love    Thank you so much!  :)

@marc sancandi 

I am so sorry to cause you trouble, I appreciate your time and concern and your comprehensive explanation. Thank you so much.

@Markiyan Hirnyk 

Thanks a lot.

@marc sancandi 

Thank you so much. It was so useful. 

@marc sancandi 

thank you so much for your answer

I have formulated my problem as a LP model, something like this:

Max z=cx

Ax>=B

A'x=B'

x>=0

but one of the parameters for example A' follows a lognormal distribution function and takes stochastic values. but the other parameters are deterministic. How can reformulate this problem to include this in it and when you look at the model you can understand the stochastic or deterministic nature of parameters? 

@tomleslie

Thank you so much for your answer.

Would you please show me how can I  formulate it as a mathematical stochastic program rather than maple code? (for example in constraints)

This may not be the right place to ask such a question, but I can't find an answer. Please help me.

@tomleslie @Kitonum you guys are genius...dunno how to thank you...:)

@Kitonum thank you very much, i thought that it would result one scalar as if production of two vectors...i wonder how it works..thank you anyway for your time and concern.

@Kitonum 

how did you do that?!  I really apreciate your the brilliant idea, thank you very much..

just how did you defined the product..can you explain it a little bit more please?

@Rouben Rostamian  

Thank you so much for your comprehensive explanations...it was great.

@Rouben Rostamian  

Thank you ... i meant the first condition that contains "x3>=2" but i can't understand how do you find the proper plotting range...can you please help me?!

@Markiyan Hirnyk

Thanks alot for your time and concern.

@Markiyan Hirnyk Thank you very much, I edited the mentioned mistakes and i got this...

Mu(x1, x2, x3) = piecewise(`or`(`or`(x1 > 55, x2 > 10), x3 >= 2), 1, x1 < 35 and x2 <= 10 and x3 < 1, (1/10)*x2, `and`(`and`(x1 < 35 and x2 <= 10, x3 >= 1), x3 <= 2), max((1/10)*x2, x3-1), `and`(`and`(`and`(x1 >= 35, x1 <= 55), x2 <= 10), x3 <= 1), 1-((55-x1)*(1/20))*((10-x2)*(1/10)), `and`(`and`(`and`(`and`(x1 >= 35, x1 <= 55), x2 <= 10), x3 >= 1), x3 <= 2), max(x3-1, 1-((55-x1)*(1/20))*((10-x2)*(1/10))))

but still can't get a 3D plot of it...I think it's because i have 4 parameters here...i want to plot it for just 3 values of Mu (0,0.5,1) but i don't know how to put it in code...can you help me please?!