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Re: [Bug-glpk] Different generated model on ARMv7 and x86-64

From: Heinrich Schuchardt
Subject: Re: [Bug-glpk] Different generated model on ARMv7 and x86-64
Date: Sun, 6 Aug 2017 20:50:25 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1

On 08/06/2017 08:20 PM, Andrew Makhorin wrote:
>> In the first two cases evaluation of pt precedes evaluation of xt while
>> in the last three cases xt is evaluated before pt. At the moment I
>> cannot say why this happens...
> I'm sure that this happens, because in the first two cases arguments
> passed to a function (I mean C code, not MathProg) are evaluated in one
> order while in the last three cases in some different order. For
> example, to add two linear forms the following statement is used in
> mpl3.c (see line 4754):
> value = linear_comb(mpl,
>            +1.0, eval_formula(mpl, code->arg.arg.x,
>            +1.0, eval_formula(mpl, code->arg.arg.y);
> where the order in which eval_formula is called depends on the platform.

      FORMULA *op1;
      FORMULA *op2;
         case O_ADD:
            /* addition */
            op1 = eval_formula(mpl, code->arg.arg.x);
            op2 = eval_formula(mpl, code->arg.arg.y);
            value = linear_comb(mpl,
               +1.0, op1,
               +1.0, op2);

gives same result on both arm64 and x86-64.

I suggest you change all binary operands.

Best regards

Heinrich Schuchardt

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