W3School TIY Editor
W3School 在线教程
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暗黑模式
<!DOCTYPE html> <html> <body> <?php echo(atanh(M_PI_4) . "<br>"); echo(atanh(0.50) . "<br>"); echo(atanh(-0.50) . "<br>"); echo(atanh(1) . "<br>"); echo(atanh(-1)); ?> </body> </html>