Error with token amount calculation

[tushar-sahoo]

So I was trying to buy tokens worth 0.001 SOL. But instead the calculation you provided bought tokens 0.000000034 SOL.

https://solscan.io/tx/2w62deyJ3uGhZerxSr1XrGJPFWjvLpkzW9cYHuBFPbmB6Dnp7yG14xMtf1vAX1F3sUs1TnhsBE5Rh1ZQ2ZBoGyYb

This is the transaction. I have no idea what is wrong with my calculations.

        const structure = struct([
            u64('discriminator'),
            u64('virtualTokenReserves'),
            u64('virtualSolReserves'),
            u64('realTokenReserves'),
            u64('realSolReserves'),
            u64('tokenTotalSupply'),
        ]);

        const value = structure.decode(ataInfo.data);
        const amount = BigInt(maxLamports / LAMPORTS_PER_SOL);

        const virtualSolReserves = BigInt(value.virtualSolReserves);
        const virtualTokenReserves = BigInt(value.virtualTokenReserves);
        const realTokenReserves = BigInt(value.realTokenReserves);

        const n = virtualSolReserves * virtualTokenReserves;
        const i = virtualSolReserves + amount;
        const r = n / i + 1n;
        const s = virtualTokenReserves - r;

        const tokens = s < realTokenReserves ? s : realTokenReserves;

        return Number(tokens);

[zLikeMario]

这个 tokens 指的是 代币的数量，而不是 sol 的数量，因为有滑点的原因，所以，你购买的时候需要传入你想要支付的最大 sol 和 你想要得到的 代币

[tushar-sahoo]

@YaminZheng I am not looking to buy a pre determined number of tokens. I am looking to buy whatever the amount of tokens is possible for a pre determined number of SOL (say 0.1 SOL).

[zLikeMario]

对，你可以看库里的。getBuyInstructions 方法，他的第四个参数就是 token 数量，第五个参数就是你愿意花费的 sol 的数量，如果你想要花费 0.1 sol ，那 第四个参数就是 0.1sol 通过 getBuyPrice 计算出来的 token 数量

[tushar-sahoo]

@YaminZheng I did do the same for the transaction below. But the buy amount was way less.

https://solscan.io/tx/2w62deyJ3uGhZerxSr1XrGJPFWjvLpkzW9cYHuBFPbmB6Dnp7yG14xMtf1vAX1F3sUs1TnhsBE5Rh1ZQ2ZBoGyYb

[yudizaxay]

您好 @YaminZheng，如果您能告诉我，将非常有帮助。有什么方法可以计算 SOL 可以以给定数量购买的代币的估计数量？

[zhengyimeng]

tokenAmount = getBuyPrice(solAmount)

[icaca]

When using jup to purchase pump, you can use sol as the standard. Previously, pump seemed to be standard on tokens. Now there is a tab on the website that allows you to use sol or token as the standard.