# Simple Convex Optimization

``````C_1 = 0.5; C_2 = 0.8; C_3 = 0.4; C_5 = 0.3;

cvx_begin
variable A
minimize( (C_1.*(1 - A)).*(2.^(C_2./(1 - A)) - 1) + (C_3.*A).*(2.^(C_4./A) - 1))
subject to
0 < A < 1;
cvx_end
``````

I have the above convex optimization problem but the following error appears.

Error using .* (line 173)
Disciplined convex programming error:
Cannot perform the operation: {positive constant} ./ {real affine}

Error in ./ (line 19)
z = times( x, y, β./β );

I tried to fix it after reading the division rule but still cannot figure out what is wrong

Perhaps itβs not quite as simple as you imply.

You will need to use 2 separate exponential cone constraints.

Expression of the form
`y*exp(x/y)` , with y > 0, will need to be replaced by a new variable `z` and the constraint
{x,y,z} == exponential(1)

You will need this to be `z1` for the expression involving `1-A`, in which `1-A` will be the `y`. And `z2` for the expression involving `A`, for which `A` will be the `y`. You will need to convert `2^(b/c)` to `exp(b*log(2)/c)`before doing this.

I will let you work through the details so that you learn something.

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Thanks so much for your help.