function create_tab_builder(div, selector){
    //create the contract, buy subcurrency, create the market, teach oracle text 
    var ZERO = btoa(array_to_string(integer_to_array(0, 32)));
    var display = document.createElement("div");
    var title = document.createElement("h3");
    title.innerHTML = "Create a new synthetic asset and a market for it ";
    div.appendChild(title);
    div.appendChild(br());
    div.appendChild(display);
    div.appendChild(br());
    var selector_label = document.createElement("span");
    selector_label.innerHTML = "source currency (i.e. the collateral backing the synthetic asset): ";
    div.appendChild(selector_label);
    div.appendChild(selector);
    div.appendChild(br());

    var normal_div = document.createElement("div");
    var stablecoin_div = document.createElement("div");
    var current_div = document.createElement("div");
    current_div.appendChild(stablecoin_div);

    var website_text = document.createElement("select");
    var option_qtrade = document.createElement("option");
    option_qtrade.innerHTML = "qtrade.io";
    option_qtrade.value = "qtrade.io";
    var option_cmc = document.createElement("option");
    option_cmc.innerHTML = "coinmarketcap.com";
    option_cmc.value = "coinmarketcap.com";
    var option_cp = document.createElement("option");
    option_cp.innerHTML = "coinpaprika.com";
    option_cp.value = "coinpaprika.com";
    var option_ed = document.createElement("option");
    option_ed.innerHTML = "euromomo.eu/graphs-and-maps";
    option_ed.value = "euromomo.eu/graphs-and-maps";
    website_text.appendChild(option_qtrade);
    website_text.appendChild(option_cmc);
    website_text.appendChild(option_cp);
    website_text.appendChild(option_ed);
    var ticker_text = text_input("Ticker of Synthetic Asset (i.e. BTC)", stablecoin_div);
    stablecoin_div.appendChild(br());
    website_label = document.createElement("span");
    website_label.innerHTML = "website to convert the VEO price to the price of your stablecoin.";
    stablecoin_div.appendChild(website_label);
    stablecoin_div.appendChild(website_text);
    stablecoin_div.appendChild(br());

    var day_label = document.createElement("span");
    day_label.innerHTML = "day of the month when the value is measured";
    stablecoin_div.appendChild(day_label);
    var select_day = document.createElement("select");
    add_days(select_day, 1, 34);
    var d = new Date();
    select_day.value = d.getDate();
    stablecoin_div.appendChild(select_day);
    stablecoin_div.appendChild(br());
    
    var month_label = document.createElement("span");
    month_label.innerHTML = "month when the value is measured";
    stablecoin_div.appendChild(month_label);
    var select_month = document.createElement("select");
    add_months(select_month);
    var d = new Date();
    select_month.value = (1 + d.getMonth()).toString();
    stablecoin_div.appendChild(select_month);
    stablecoin_div.appendChild(br());
    
    var year_label = document.createElement("span");
    year_label.innerHTML = "year when the value is measured";
    stablecoin_div.appendChild(year_label);
    var select_year = document.createElement("select");
    add_days(select_year, 2020, 2022);
    var d = new Date();
    select_year.value = d.getFullYear().toString();
    stablecoin_div.appendChild(select_year);
    stablecoin_div.appendChild(br());

    var coll_text = text_input("collateralization (i.e. \"2\" means 200%)", stablecoin_div);
    stablecoin_div.appendChild(br());
    var starting_price_text = text_input("starting price of veo in your target currency (i.e. 0.0002 BTC per VEO)", stablecoin_div);
    stablecoin_div.appendChild(br());
    var amount_text = text_input("amount of source currency to put into the market as liquidity", div);
    div.appendChild(br());
    div.appendChild(current_div);

    var stablecoin_button = button_maker2("make contract", make_stablecoin_contract);
    stablecoin_div.appendChild(stablecoin_button);
    div.appendChild(br());

    function add_months(select_month) {
        var x =
            [["january", 1],
             ["febuary", 2],
             ["march", 3],
             ["april", 4],
             ["may", 5],
             ["june", 6],
             ["july", 7],
             ["august", 8],
             ["september", 9],
             ["october", 10],
             ["november", 11],
             ["december", 12]];
        for(var i = 0; i< x.length; i++){
            var option = document.createElement("option");
            option.innerHTML = x[i][0];
            option.value = x[i][1];
            select_month.appendChild(option);
        };
             
    };
    function add_days(select_day, N, Limit){
        for(var i = N; i<Limit; i++){
            var option = document.createElement("option");
            option.innerHTML = i;
            option.value = i;
            select_day.appendChild(option);
        };
    };
    function make_stablecoin_contract(){
        var website = website_text.value;
        var time = "12:00 "
            //.concat(day_text.value)
            .concat(select_day.value.toString())
            .concat("-")
            .concat(select_month.value)
            .concat("-")
            //.concat(year_text.value);
            .concat(select_year.value);
        var ticker = ticker_text.value.trim().toUpperCase();
        var coll = parseFloat(coll_text.value);
        var starting_price = parseFloat(starting_price_text.value);
        console.log([coll, starting_price]);
        //var MP = coll * starting_price;
        var MaxVal = 4294967295;
        var Scale = Math.round(MaxVal / starting_price * coll);
        //var MP = MaxVal;
        var Text_old = "W = "
            .concat(website)
            .concat("; T = ")
            .concat(time)
            .concat(" China Standard Time (GMT+8); ticker = ")
            .concat(ticker)
            .concat("; return(the price of ticker at time T according to website W) * ")
            .concat(Scale);
        if(ticker === "BTC") {
            var Text = "standard stablecoin 0; ticker_path = [VEO, BTC]; website_path = [qtrade.io]; time = "
                .concat(time)
                .concat(" China Standard Time (GMT+8); price = 1; for(i=0; i<website_path.length; i++){price *= (the price of ticker_path[i] in ticker_path[i+1] according to website[i])}; scale = ")
                .concat(Scale)
                .concat("; return(price * scale);");
        } else {
            var Text = "standard stablecoin 0; ticker_path = [VEO, BTC, "
                .concat(ticker)
                .concat("]; website_path = [qtrade.io, ")
                .concat(website)
                .concat("]; time = ")
                .concat(time)
                .concat(" China Standard Time (GMT+8); price = 1; for(i=0; i<website_path.length; i++){price *= (the price of ticker_path[i] in ticker_path[i+1] according to website[i])}; scale = ")
                .concat(Scale)
                .concat("; return(price * scale);");
        }
        var price = 1/(coll);
        var amount = Math.round(parseFloat(amount_text.value)*token_units());
        return(make_contract2(Text, MaxVal, price, amount, display, selector));
    };
    async function make_txs(Text, MP, price, amount, display2, selector2_value) {
    
        var amount1 = amount*price;
        var amount2 = amount*(1-price);

        if(MP<1){
            display2.innerHTML = "max price must be an integer greater than 0.";
            return(0);
        }
        var Source, SourceType;
        if(selector2_value == "veo"){
            Source = ZERO;
            SourceType = 0;
        } else {
            var V = JSON.parse(selector2_value);
            Source = V[0];
            SourceType = V[1];
        }
           
        //var price = amount1 / amount2; 
        var source_amount = amount;
        var new_contract_tx =
            new_scalar_contract.make_tx(
                Text, MP, Source, SourceType);
        var CH = new_contract_tx[2];
        var cid = merkle.contract_id_maker(CH, 2, Source, SourceType);
        var txs = [new_contract_tx];
        if (source_amount == 0) {
            
        } else if (amount1 == amount2) {
            txs = txs.concat([
                ["contract_use_tx", 0,0,0,
                 cid, amount, 2,
                 Source, SourceType],
                ["market_new_tx", 0,0,0,
                 cid, cid, 1, 2,
                 amount-1000, amount-1000],
                ["market_new_tx",0,0,0,
                 Source,cid,SourceType,1,
                 1000, 1000],
                ["market_new_tx",0,0,0,
                 Source,cid,SourceType,2,
                 1000, 1000]
            ]);
        } else if (amount1 > amount2){
            //T = total veo invested.
            //P = initial probability of type 1.

            //a1 is the more valuable kind.

            //M1 = [V, A1]
            //M2 = [A2, B]

            // A1 + A2 = B
            // V + B = T
            // P = V / A1
            // P/(1-P) = B / A2

            //get rid of the Vs
            // A1 + A2 = B
            // P*A1 + B = T
            // P/(1-P) = B / A2

            //get rid of the A1s
            // P*(B-A2) + B = T
            // P/(1-P) = B / A2
            // -> A2 = B*(1-P)/P

            //get rid of the A2s
            //P*(B-(B*(1-P)/P)) + B = T
            // -> B(P(1-((1-P)/P))) + B = T
            // B(P-(1-P))+B = T
            //B(2P-1)+B = T
            //B(1+(2P-1)) = T
            //B(2P) = T
            //B = T/2/P
            //V = T-B = T(1 - 1/(2*P)) = T(2P - 1)/(2p)
            //V = T - B
            //A1 = V/P
            //A2 = B - A1

            
            //A1 = B(1-P)
            //A2 = B*P
            
            var T = amount;
            var P = price;
            var B = Math.round(amount/2/P);
            var V = Math.round(T - B);
            //var A1 = Math.round(B*(1-P));
            //var A2 = Math.round(B*P);
            //var A1 = Math.round(V*P);
            //var A2 = B-A1;
            var A1 = Math.round(V/P);
            var A2 = Math.round(B - A1);

            txs = txs.concat([
                ["contract_use_tx", 0,0,0,
                 cid, B, 2,
                 Source, SourceType],
                ["market_new_tx",0,0,0,
                 cid,cid,1,2,
                 A2, B-1000],
                ["market_new_tx",0,0,0,
                 Source,cid,SourceType,1,
                 V, A1],
                ["market_new_tx",0,0,0,
                 Source,cid,SourceType,2,
                 1000, 1000]
            ]);
        } else if (amount2 > amount1){
            var T = amount;
            var P = 1 - price;
            //var B = Math.round(T*(P/(P + ((1+P)*(1-P)))));
            var B = Math.round(amount/2/P);
            //var B = Math.round(amount/2/(1 - ((1-P)/4)));
            var V = Math.round(T - B);
            //var A1 = Math.round(B*(1-P));
            //var A2 = Math.round(B*P);
            //var A1 = Math.round(V*P);
            var A1 = Math.round(V/P);
            var A2 = B-A1;
            txs = txs.concat([
                ["contract_use_tx", 0,0,0,
                 cid, B, 2,
                 Source, SourceType],
                ["market_new_tx",0,0,0,
                 cid,cid,2,1,
                 A2, B-1000],
                ["market_new_tx",0,0,0,
                 Source,cid,SourceType,1,
                 1000, 1000],
                ["market_new_tx",0,0,0,
                 Source,cid,SourceType,2,
                 V, A1]
            ]);
        };
        var msg =
            ["add", 3, btoa(Text),
             0, MP, Source,
             SourceType];
        var x = await rpc.apost(msg, get_ip(), 8090);
        console.log(JSON.stringify(x));
        console.log("taught a scalar contract.");
        return(txs);
    };
        
    async function make_contract2(Text, MP, price, amount, display2, selector2) {
        var txs = await make_txs(Text, MP, price, amount, display2, selector2.value);

        var tx = await multi_tx.amake(txs);
        var stx = keys.sign(tx);
        var msg = await apost_txs([stx]);
        var CH = txs[0][2];
        var Source = txs[0][5];
        var SourceType = txs[0][6];
        var cid = merkle.contract_id_maker(CH, 2, Source, SourceType);
        msg = msg.concat("<br>contract id: ")
            .concat(cid)
        ;
        display2.innerHTML = msg;
        if(!(msg == "server rejected the tx")){
            keys.update_balance();
        };
    };
    return({
        website:(function(x){website_text.value = x}),
        coll:(function(x){coll_text.value = x}),
        starting_price:(function(x){starting_price_text.value = x}),
        ticker:(function(x){ticker_text.value = x}),
        amount:(function(x){amount_text.value = x}),
        make_contract2: make_contract2,
        make_txs: make_txs
    });
};