Error: vcPower: GRAD SINGULAR: x**c, x=0, 0<c<1

GAMS
1

Reply-to: gamsworld@googlegroups.com

hi,
i am a beginner user of GAMS, i am running a nonlinear programming
model minimizing a squared deviation between two variables d and x.
and i get errors in the solution
Error: vcPower: GRAD SINGULAR: x**c, x=0, 0<c<1


the model is as follows:
min s =e= sum((j,k)$(ord(k) lt ord(j)), e(j,k)**2);
subject to

eq_1(j,k)$(ord(k) lt ord(j))…d(j,k)- (sum(r, (x(j,r)-
x(k,r))**2))**0.5- e(j,k)=e=0;

eq_3(r)… sum(j, x(j,r))=e=0;

eq_4… sum((j,k,r)$(ord(k) lt ord(j)), (x(j,r)-x(k,r))**2)=e=1;

i don’t know how to solve this problem and get rid of this error, and
what does this error mean
can anyone help me?
thanks in advance

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2

Gams manual page 54:
x**nn is calculated as exp(n*log(x)) for x=0 this is not determined.

Change

e(j,k)**2

x(k,r))**2

with
pow (e(j,k),2)
pow(x(k,r),2)

Gams manual page

hi,
i am a beginner user of GAMS, i am running a nonlinear programming
model minimizing a squared deviation between two variables d and x.
and i get errors in the solution
Error: vcPower: GRAD SINGULAR: x**c, x=0, 0

the model is as follows:
min s =e= sum((j,k)$(ord(k) lt ord(j)), e(j,k)**2);
subject to

eq_1(j,k)$(ord(k) lt ord(j))…d(j,k)- (sum(r, (x(j,r)-
x(k,r))**2))**0.5- e(j,k)=e=0;

eq_3(r)… sum(j, x(j,r))=e=0;

eq_4… sum((j,k,r)$(ord(k) lt ord(j)), (x(j,r)-x(k,r))**2)=e=1;

i don’t know how to solve this problem and get rid of this error, and
what does this error mean
can anyone help me?
thanks in advance

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3

thanks alot
i tried the power function and and it works without errors
thank you very much

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4

Dear Edsoncv:

I have the same problem as Rugiada. This error comes from my production functions, for example like this:

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 already tried your suggestion; however, the error has not been corrected.

Could you please advise me any other suggestion to correct this error.

Thank you so much for your help

Loan

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

i am a beginner user of GAMS, i am running a nonlinear programming
model minimizing a squared deviation between two variables d and x.
and i get errors in the solution
Error: vcPower: GRAD SINGULAR: x**c, x=0, 0

the model is as follows:
min s =e= sum((j,k)$(ord(k) lt ord(j)), e(j,k)**2);
subject to

eq_1(j,k)$(ord(k) lt ord(j))…d(j,k)- (sum(r, (x(j,r)-
x(k,r))**2))**0.5- e(j,k)=e=0;

eq_3(r)… sum(j, x(j,r))=e=0;

eq_4… sum((j,k,r)$(ord(k) lt ord(j)), (x(j,r)-x(k,r))**2)=e=1;

i don’t know how to solve this problem and get rid of this error, and
what does this error mean
can anyone help me?
thanks in advance

–
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