/* http://alivenalone.xtgem.com */


function addChar(input, character) {

if(input.value == null || input.value == "0")

input.value = character

else

input.value += character

}



function cos(form) {

form.display.value = Math.cos(form.display.value);

}



function sin(form) {

form.display.value = Math.sin(form.display.value);

}



function tan(form) {

form.display.value = Math.tan(form.display.value);

}



function sqrt(form) {

form.display.value = Math.sqrt(form.display.value);

}



function ln(form) {

form.display.value = Math.log(form.display.value);

}



function exp(form) {

form.display.value = Math.exp(form.display.value);

}



function deleteChar(input) {

input.value = input.value.substring(0, input.value.length - 1)

}



function changeSign(input) {

if(input.value.substring(0, 1) == "-")

input.value = input.value.substring(1, input.value.length)

else

input.value = "-" + input.value

}



function compute(form) {

form.display.value = eval(form.display.value)

}



function square(form) {

form.display.value = eval(form.display.value) * eval(form.display.value)

}



function checkNum(str) {

for (var i = 0; i < str.length; i++) {

var ch = str.substring(i, i+1)

if (ch < "0" || ch > "9") {

if (ch != "/" && ch != "*" && ch != "+" && ch != "-" && ch != "."

&& ch != "(" && ch!= ")") {

alert("invalid entry!")

return false

}

}

}

return true

}


/*Design by dj 
http://... 
Icq: _ _ _-_ _ _*/