uote=abhosekar post_id=29253 time=1637252514 user_id=1684]

what you show in equations and what you are writing in GAMS are two very different equations. Which one is right?

Based on what you wrote, your equation should be

```
ir =g= 0.0055*Qi**(-0.47)
ir =l= 4.65*Qf**(-0.67)
```

not sure how that translates to what you have in the code block.

Hi,

Yes, it is different

If I put as

```
ir =g= 0.0055*Qi**(-0.47)
ir =l= 4.65*Qf**(-0.67)
```

GAMS return

```
8 error(s): vcPower: FUNC DOMAIN: x**c, x=0, c<0
```

If I put as

```
ir *Qi**(0.47)=g= 0.0055
ir*Qf**(0.67) =l= 4.65
```

GAMS return

```
3 warning(s): vcPower: GRAD SINGULAR: x**c, x=0, 0<c<1
```

So I changed

" **(-0.47)", and I multiplied Q to the other side of the equation.

0,47 to a fraction (7/15) and 0,67 (2/3), because GAMS does not accept an exponential number lower than 1.

```
ir**15*(Qi)**7 =g= 0.0055**12 ;
ir**3 *(Qf)**2 =l= 4.65 **3 ;
```

This is the form that I not obtain an error.

But returns

“All Jacobian elements in the row are very small.”

Using SBB solver, I don’t know if this solver interferes with this equation.

I declared

POSITIVE VARIABLES ir;

ir.l = 0.0001;