GRAD SINGULAR

Archiver · June 28, 2013, 7:07pm

Dear Loan,

You might want to place a lower bound equal to a small positive number on all variables that you raise to a power.

Frank Ward

From: gamsworld@googlegroups.com [mailto:gamsworld@googlegroups.com] On Behalf Of ltloan@hcmuaf.edu.vn
Sent: Friday, June 28, 2013 10:32 AM
To: gamsworld@googlegroups.com
Subject: GRAD SINGULAR error

Dear all:

Can anyone help me to correct the error below. In my GAMS code, I wrote the production functions, for example:

QINT_G2(I)… QINT(I,‘G2’) =L= (QQINT(I,‘G1’,‘G2’)**DELTA_INT(I,‘G1’,‘G2’))*(QQINT(I,‘G2’,‘G2’)**DELTA_INT(I,‘G2’,‘G2’))
(QQINT(I,‘G3’,‘G2’)**DELTA_INT(I,‘G3’,‘G2’))(QQINT(I,‘G4’,‘G2’)**DELTA_INT(I,‘G4’,‘G2’))
(QQINT(I,‘G6’,‘G2’)**DELTA_INT(I,‘G6’,‘G2’))(QQINT(I,‘G7’,‘G2’)**DELTA_INT(I,‘G7’,‘G2’));

I have corrected by replacing the power function, but the error has not been solved.

Could you please help me to correct this error?

Thank you so much

Loan

My errors:

**** ERRORS/WARNINGS IN EQUATION QP_BIO
10 warning(s): vcPower: GRAD SINGULAR: x**c, x=0, 0<c<1

**** ERRORS/WARNINGS IN EQUATION QFUELS_G6
10 warning(s): vcPower: GRAD SINGULAR: x**c, x=0, 0<c<1

**** ERRORS/WARNINGS IN EQUATION QINT_G2(VNM)
30 warning(s): vcPower: GRAD SINGULAR: x**c, x=0, 0<c<1

**** ERRORS/WARNINGS IN EQUATION QINT_G4(VNM)
30 warning(s): vcPower: GRAD SINGULAR: x**c, x=0, 0<c<1

**** ERRORS/WARNINGS IN EQUATION QINT_G6(VNM)
25 warning(s): vcPower: GRAD SINGULAR: x**c, x=0, 0<c<1

**** ERRORS/WARNINGS IN EQUATION PRO_Q2(VNM)
20 warning(s): vcPower: GRAD SINGULAR: x**c, x=0, 0<c<1

**** ERRORS/WARNINGS IN EQUATION PRO_Q4(VNM)
20 warning(s): vcPower: GRAD SINGULAR: x**c, x=0, 0<c<1

**** ERRORS/WARNINGS IN EQUATION PRO_Q6_VNM
20 warning(s): vcPower: GRAD SINGULAR: x**c, x=0, 0<c<1

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Archiver · June 28, 2013, 9:43pm

Reply-to: gamsworld@googlegroups.com

Dear Frank Ward:

Thank you so much for your help. Could you mind clarifying your suggestion so that I can try? attached is my GAMs code, you can see the error from line 315434-56 in the .lst file, this error appears from the iteration 4, see line 4048-4055 in the .lst file.
This is the CD production function like that
Q = (input1delta1)* (input2delta2)* (input3delta3)* (input4delta4)* (input5delta5)* (input6delta6)*

QINT_G2(I)… QINT(I,‘G2’) =L= (QQINT(I,‘G1’,‘G2’)**DELTA_INT(I,‘G1’,‘G2’))*(QQINT(I,‘G2’,‘G2’)**DELTA_INT(I,‘G2’,‘G2’))
(QQINT(I,‘G3’,‘G2’)**DELTA_INT(I,‘G3’,‘G2’))(QQINT(I,‘G4’,‘G2’)**DELTA_INT(I,‘G4’,‘G2’))
(QQINT(I,‘G6’,‘G2’)**DELTA_INT(I,‘G6’,‘G2’))(QQINT(I,‘G7’,‘G2’)**DELTA_INT(I,‘G7’,‘G2’));

For this error, did you guess that one of the input variable equal to zero? To correct this, we set the lower bound and when this (I mean one of the input variable equal to zero) happens, then GAMS will take into account the lower bound we assign?

Note that I declared that all these input variables are positive?

Would you mind giving me details of your suggestion? do you mean I need to set a lower bound for these input variables?
I really appreciate your help

Best regards, Loan

On Friday, June 28, 2013 7:07:55 PM UTC+2, Frank Ward wrote:

Dear Loan,

You might want to place a lower bound equal to a small positive number on all variables that you raise to a power.

Frank Ward

From: gams...@googlegroups.com [mailto:gams...@googlegroups.com] On Behalf Of ltl…@hcmuaf.edu.vn
Sent: Friday, June 28, 2013 10:32 AM
To: gams...@googlegroups.com
Subject: GRAD SINGULAR error

Dear all:

Can anyone help me to correct the error below. In my GAMS code, I wrote the production functions, for example:

QINT_G2(I)… QINT(I,‘G2’) =L= (QQINT(I,‘G1’,‘G2’)**DELTA_INT(I,‘G1’,‘G2’))*(QQINT(I,‘G2’,‘G2’)**DELTA_INT(I,‘G2’,‘G2’))
(QQINT(I,‘G3’,‘G2’)**DELTA_INT(I,‘G3’,‘G2’))(QQINT(I,‘G4’,‘G2’)**DELTA_INT(I,‘G4’,‘G2’))
(QQINT(I,‘G6’,‘G2’)**DELTA_INT(I,‘G6’,‘G2’))(QQINT(I,‘G7’,‘G2’)**DELTA_INT(I,‘G7’,‘G2’));

I have corrected by replacing the power function, but the error has not been solved.

Could you please help me to correct this error?

Thank you so much